Ultrasound diagnostic apparatus

ABSTRACT

The ultrasound probe transmits and receives ultrasonic waves in different directions and the diagnostic apparatus body combines a plurality of images captured in the different directions of transmission and reception to produce an ultrasound image. In this process, the ultrasound diagnostic apparatus measures the temperature of the ultrasound probe to change the ultrasound transmission and reception for producing a composite ultrasound image or makes the directions of transmission and reception in the last ultrasound image in one composite ultrasound image coincide with those in the first ultrasound image in its temporally adjacent composite ultrasound image. The ultrasound diagnostic apparatus thus enables consistent ultrasound diagnosis against heat generated in the integrated circuit board of the ultrasound probe while simplifying the control of the ultrasound transmission and reception.

BACKGROUND OF THE INVENTION

The present invention relates to an ultrasound diagnostic apparatus. Theinvention more particularly relates to an ultrasound diagnosticapparatus capable of suppressing heat generation from an ultrasoundprobe while easily controlling the ultrasound transmission and receptionin spatial compounding.

Ultrasound diagnostic apparatus using ultrasound images are put topractical use in the medical field.

In general, an ultrasound diagnostic apparatus includes an ultrasoundprobe (hereinafter referred to as “probe”) and a diagnostic apparatusbody. In the ultrasound diagnostic apparatus, the probe transmitsultrasonic waves toward a subject and receives ultrasonic echoes fromthe subject. The diagnostic apparatus body electrically processes thereception signals received by and outputted from the probe to produce anultrasound image.

So-called “speckle” (speckle noise/speckle pattern) is known as a factorthat may deteriorate the image quality of an ultrasound image in theultrasound diagnostic apparatus. Speckle is white spot noise caused bythe mutual interference of scattered waves generated by numerousscattering sources which are present in a subject and have a smallerwavelength than that of an ultrasonic wave.

Spatial compounding as described in JP 2005-58321 A and JP 2003-70786 Ais known as a method of reducing such speckle in the ultrasounddiagnostic apparatus.

As conceptually shown in FIG. 34, spatial compounding is a techniquewhich involves performing a plurality of types of ultrasoundtransmission and reception in mutually different directions (at mutuallydifferent scanning angles) between a piezoelectric unit 100 and asubject, and combining ultrasound images obtained by the plurality oftypes of ultrasound transmission and reception to produce a compositeultrasound image.

More specifically, in the example shown in FIG. 34, three types ofultrasound transmission and reception are performed which include theultrasound transmission and reception as in the normal ultrasound imagegeneration (normal transmission and reception), the ultrasoundtransmission and reception in a direction inclined by an angle of θ withrespect to the direction of the normal transmission and reception, andthe ultrasound transmission and reception in a direction inclined by anangle of −θ with respect to the direction of the normal transmission andreception.

An ultrasound image A (solid line) obtained by the normal transmissionand reception, an ultrasound image B (broken line) obtained by thetransmission and reception in the direction inclined by the angle of θ,and an ultrasound image C (chain line) obtained by the transmission andreception in the direction inclined by the angle of −θ are combined toproduce a composite ultrasound image covering the region of theultrasound image A shown by the solid line.

The probe making up the ultrasound diagnostic apparatus includes apiezoelectric unit which transmits ultrasonic waves to a subject,receives ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject and outputs the received ultrasonic echoes aselectric signals (reception signals).

Recently, the probe may also be provided with an integrated circuitboard for use in amplifying the reception signals outputted from thepiezoelectric unit, performing A/D conversion or other processing,changing the timing of transmission and reception of ultrasonic waves inthe piezoelectric unit, wireless communication with the diagnosticapparatus body without using any cord, and reducing noise.

As well known, the piezoelectric unit generates heat through theultrasound transmission and reception.

Higher-definition ultrasound images are obtained with increasing powerof ultrasonic waves transmitted from the piezoelectric unit. However,the amount of heat generated from the piezoelectric unit is alsoincreased with increasing power of ultrasonic waves transmitted from thepiezoelectric unit.

The integrated circuit board also generates heat through receptionsignal processing.

That is, the probe generates heat through ultrasound transmission andreception.

The heat generation from the probe destabilizes the drive of thepiezoelectric unit and the operation of each circuit of the integratedcircuit board. As a result, output signals from the transmitted orreceived ultrasonic waves are destabilized to further destabilize thesignal processing in the integrated circuit board. That is, the heatgeneration from the probe lowers the image quality of ultrasound images.

Therefore, it is necessary in the ultrasound diagnostic apparatus tosuppress the temperature increase within the probe as much as possiblein order to consistently obtain high-definition ultrasound images.

As also described above, spatial compounding enables speckle on theresulting ultrasound image to be reduced.

On the other hand, since the directions of ultrasound transmission andreception are to be changed for each ultrasound image used to produce acomposite ultrasound image, the control of ultrasound transmission andreception becomes complicated.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the foregoing prior artproblems and to provide an ultrasound diagnostic apparatus which, when acomposite ultrasound image is produced from ultrasound images by spatialcompounding, is capable of suppressing the temperature increase withinthe ultrasound probe while minimizing the image quality deterioration ofultrasound images even if the temperature is increased.

Another object of the invention is to provide an ultrasound diagnosticapparatus capable of reducing the switching control of the directions ofultrasound transmission and reception in the production of an ultrasoundimage through spatial compounding, thereby simplifying the control ofthe ultrasound transmission and reception upon spatial compounding.

In order to achieve the above objects, a first aspect of the inventionprovides an ultrasound diagnostic apparatus comprising:

an ultrasound probe configured to transmit ultrasonic waves into asubject and receive ultrasonic echoes generated by reflection of theultrasonic waves from the subject, the ultrasound probe including asignal processor for processing reception signals based on theultrasonic echoes and a temperature sensor for measuring a temperatureat a predetermined position; and

a diagnostic apparatus body configured to generate ultrasound images inaccordance with the reception signals processed in the signal processorof said ultrasound probe,

wherein said ultrasound probe is configured to perform a plurality oftypes of ultrasound transmission and in mutually different directions ofultrasound transmission and reception and said diagnostic apparatus bodyis configured to combine ultrasound images based on each of theplurality of types of ultrasound transmission and reception, and

wherein, upon production of the composite ultrasound image in saiddiagnostic apparatus body, said ultrasound probe is configured to changeultrasound transmission and reception for producing said compositeultrasound image in accordance with a temperature measurement resultobtained with said temperature sensor.

In the ultrasound diagnostic apparatus according to the first aspect ofthe invention, upon the production of the composite ultrasound image inthe diagnostic apparatus body, the ultrasound probe preferably performsthe ultrasound transmission and reception for producing the compositeultrasound image through the plurality of types of ultrasoundtransmission and reception or through at least one type of ultrasoundtransmission and reception after reduction of one or more types ofultrasound transmission and reception from the plurality of types ofultrasound transmission and reception based on the temperaturemeasurement result obtained with the temperature sensor.

The temperature sensor preferably measures a temperature of the signalprocessor.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, the ultrasound probe preferably performs ultrasoundtransmission and reception for obtaining a main image as an ultrasoundimage in a preset predetermined output region by one of the plurality oftypes of ultrasound transmission and reception.

Preferably, a temperature T1 and a temperature T2 higher than thetemperature T2 are set as thresholds and, upon the production of thecomposite ultrasound image in the diagnostic apparatus body, dependingon the temperature measurement result obtained with the temperaturesensor, the ultrasound probe performs the plurality of types ofultrasound transmission and reception when the temperature measurementresult is less than the temperature T1, performs a set minimum number oftypes of ultrasound transmission and reception when the temperaturemeasurement result is equal to or more than the temperature T2, andperforms a given number of types of ultrasound transmission andreception which is smaller than the number of the plurality of types oftransmission and reception but is larger than the set minimum number oftypes of ultrasound transmission and reception when the temperaturemeasurement result is equal to or more than the temperature T1 but lessthan the temperature T2.

Preferably, a temperature T1 and a temperature T2 higher than thetemperature T2 are set as thresholds and, upon the production of thecomposite ultrasound image in the diagnostic apparatus body, dependingon the temperature measurement result obtained with the temperaturesensor, the ultrasound probe performs the plurality of types ofultrasound transmission and reception when the temperature measurementresult is less than the temperature T1, and when the temperaturemeasurement result is equal to or more than the temperature T1,performs, in one composite ultrasound image, the at least one type ofultrasound transmission and reception after the reduction of the one ormore types of ultrasound transmission and reception from the pluralityof types of ultrasound transmission and reception and performs, in itstemporally consecutive composite ultrasound image, the plurality oftypes of ultrasound transmission and reception or the at least one typeof ultrasound transmission and reception after the reduction of the oneor more types of ultrasound transmission and reception from theplurality of types of ultrasound transmission and reception, a number oftypes of ultrasound transmission and reception reduced from the numberof the plurality of types of ultrasound transmission and reception beingdifferent in two consecutive ultrasound images including the onecomposite ultrasound image and its temporally consecutive compositeultrasound image. The ultrasound probe preferably performs theultrasound transmission and reception by reducing the one or more typesof ultrasound transmission and reception from the plurality of types ofultrasound transmission and reception in one of the two temporallyconsecutive composite ultrasound images when the temperature measurementresult is equal to or more than the temperature T1 but less than thetemperature T2.

The ultrasound probe preferably performs the ultrasound transmission andreception by reducing the one or more types of ultrasound transmissionand reception from the plurality of types of ultrasound transmission andreception in both of the two temporally consecutive composite ultrasoundimages when the temperature measurement result is equal to or more thanthe temperature T2.

The ultrasound probe preferably transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, the ultrasound probe preferably performs the ultrasoundtransmission and reception so as to reduce temporally consecutiveultrasound image when two or more types of ultrasound transmission andreception are reduced from the plurality of types of ultrasoundtransmission and reception.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, the ultrasound probe preferably performs the ultrasoundtransmission and reception so as to reduce a last ultrasound image in acomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image when the one or moretypes of ultrasound transmission and reception are reduced from theplurality of types of ultrasound transmission and reception.

In the ultrasound diagnostic apparatus according to the first aspect ofthe invention, upon the production of the composite ultrasound image inthe diagnostic apparatus body, the ultrasound probe preferably adjustsconditions of the ultrasound transmission and reception so as to changean image quality of an ultrasound image to be combined in the diagnosticapparatus body in accordance with the temperature measurement resultobtained with the temperature sensor.

The temperature sensor preferably measures a temperature of the signalprocessor.

The ultrasound probe preferably changes at least one of a number ofavailable channels and a number of sound rays to adjust the conditionsof the ultrasound transmission and reception.

Preferably, a temperature T3 and a temperature T4 higher than thetemperature T3 are set as thresholds, and ultrasound transmission andreception at a normal image quality level corresponding to ultrasoundimages of predetermined image quality, ultrasound transmission andreception at a low image quality level corresponding to ultrasoundimages of lowest image quality, and ultrasound transmission andreception at a medium image quality level corresponding to ultrasoundimages having image quality lower than the normal image quality levelbut higher than the low image quality level are set in the conditions ofthe ultrasound transmission and reception for obtaining the ultrasoundimage to be combined.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsall of the plurality of types of ultrasound transmission and receptionat the normal image quality level when the temperature measurementresult is less than the temperature T3.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performs atleast two of the plurality of types of ultrasound transmission andreception at the medium image quality level when the temperaturemeasurement result is equal to or more than the temperature T3 but lessthan the temperature T4 and at the low image quality level when thetemperature measurement result is equal to or more than the temperatureT4.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performs atleast two of the plurality of types of ultrasound transmission andreception at the medium image quality level when the temperaturemeasurement result is equal to or more than the temperature T3 but lessthan the temperature T4, and performs at least one of the plurality oftypes of ultrasound transmission and reception at the medium imagequality level and one or more types of ultrasound transmission andreception except the at least one of the plurality of types ofultrasound transmission and reception at the low image quality levelwhen the temperature measurement result is equal to or more than thetemperature T4.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performs atleast two of the plurality of types of ultrasound transmission andreception at the medium image quality level when the temperaturemeasurement result is equal to or more than the temperature T3 but lessthan the temperature T4, and performs the at least two of the pluralityof types of ultrasound transmission and reception at the low imagequality level and all of one or more types of ultrasound transmissionand reception except the at least two of the plurality of types ofultrasound transmission and reception at the medium image quality levelwhen the temperature measurement result is equal to or more than thetemperature T4.

Preferably, upon the production of the composite ultrasound image in thediagnostic apparatus body, the ultrasound probe performs ultrasoundtransmission and reception for obtaining a main image as an ultrasoundimage in a preset predetermined output region by one of the plurality oftypes of ultrasound transmission and reception and the ultrasoundtransmission and reception for the main image are performed at thenormal image quality level.

The ultrasound probe preferably transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.

In the ultrasound diagnostic apparatus according to the first aspect ofthe invention, upon the production of the composite ultrasound image inthe diagnostic apparatus body, the ultrasound probe preferably adjusts adepth of the reception signals to be processed by the signal processorso as to change a depth of an ultrasound image to be combined in thediagnostic apparatus body in accordance with the temperature measurementresult obtained with the temperature sensor.

The temperature sensor preferably measures a temperature of the signalprocessor.

Preferably, a temperature T5 and a temperature T6 higher than thetemperature T5 are set as thresholds and a normal depth according towhich the reception signals are processed up to a predetermined depth, asmall depth according to which the reception signals are processed up toa shallowest depth and a medium depth according to which the receptionsignals are processed up to a depth smaller than the normal depth butlarger than the small depth are set for the depth of the receptionsignals to be processed by the signal processor.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsall of reception signal processing in the plurality of types ofultrasound transmission and reception up to the normal depth when thetemperature measurement result is less than the temperature T5.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsreception signal processing in at least two of the plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6 and up to the small depth when thetemperature measurement result is equal or more than the temperature T6.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsreception signal processing at least two of the plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6, and alternately repeats receptionsignal processing up to the small depth in at least two of the pluralityof types of ultrasound transmission and reception and reception signalprocessing up to the medium depth in the at least two of the pluralityof types of ultrasound transmission and reception in temporallyconsecutive composite ultrasound images when the temperature measurementresult is equal to or more than the temperature T5.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsreception signal processing in at least two of the plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6 and performs reception signalprocessing in at least one of the plurality of types of ultrasoundtransmission and reception up to the medium depth and one or more typesof ultrasound transmission and reception except the at least one of theplurality of types of ultrasound transmission and reception up to thesmall depth when the temperature measurement result is equal to or morethan the temperature T6.

Ultrasound images subjected to the reception signal processing up to themedium depth and ultrasound images subjected to the reception signalprocessing up to the small depth are preferably different in order ofprocessing in temporally consecutive composite ultrasound images whenthe temperature measurement result is equal to or more than thetemperature T6.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably performsreception signal processing in at least two of the plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6 and performs the reception signalprocessing in the at least two of the plurality of types of ultrasoundtransmission and reception up to the small depth and all of one or moretypes of ultrasound transmission and reception except the at least twoof the plurality of types of ultrasound transmission and reception up tothe medium depth when the temperature measurement result is equal to ormore than the temperature T6.

Preferably, upon the production of the composite ultrasound image in thediagnostic apparatus body, the ultrasound probe performs ultrasoundtransmission and reception for obtaining a main image as an ultrasoundimage in a preset predetermined output region by one of the plurality oftypes of ultrasound transmission and reception and reception signalsobtained by the ultrasound transmission and reception for the main imageare processed up to the normal depth.

The ultrasound probe preferably transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.

In the ultrasound diagnostic apparatus according to the first aspect ofthe invention, upon the production of the composite ultrasound image inthe diagnostic apparatus body, the ultrasound probe preferably adjustsreception signal processing performed by the signal processor so as toreduce a number of sound rays in a region beyond a predetermined depthin an ultrasound image to be combined by the diagnostic apparatus bodydepending on the temperature measurement result obtained with thetemperature sensor, and upon the production of the composite ultrasoundimage in the diagnostic apparatus body, the diagnostic apparatus bodyinterpolates sound rays eliminated beyond the predetermined depth withtheir surrounding sound rays to produce the ultrasound image.

The temperature sensor preferably measures a temperature of the signalprocessor.

Preferably, a temperature T7 and a temperature T8 higher than thetemperature T7 are set as thresholds, and a normal depth up to which thenumber of sound rays is not reduced, a small depth which is shallowest,and a medium depth which is smaller than the normal depth but is largerthan the small depth are set for the predetermined depth beyond whichthe number of sound rays is reduced.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably processesall of ultrasound images up to the normal depth when the temperaturemeasurement result is less than the temperature T7.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably reduces thenumber of sound rays beyond the medium depth in at least two ofultrasound images when the temperature measurement result is equal to ormore than the temperature T7 but less than the temperature T8, andreduces the number of sound rays beyond the small depth in the at leasttwo of ultrasound images when the temperature measurement result isequal to or more than the temperature T8.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably reduces thenumber of sound rays beyond the medium depth in at least two ofultrasound images when the temperature measurement result is equal to ormore than the temperature T7 but less than the temperature T8, andreduces the number sound rays beyond the medium depth in at least one ofultrasound images and one or more ultrasound images except the at leastone of ultrasound images beyond the small depth when the temperaturemeasurement result is equal to or more than the temperature T8.

Upon the production of the composite ultrasound image in the diagnosticapparatus body, depending on the temperature measurement result obtainedwith the temperature sensor, the ultrasound probe preferably reduces thenumber of sound rays beyond the medium depth in at least two ofultrasound images when the temperature measurement result is equal to ormore than the temperature T7 but less than the temperature T8, andreduces the number of sound rays beyond the small depth in the at leasttwo of ultrasound images and all of one or more ultrasound images exceptthe at least two of ultrasound images beyond the medium depth when thetemperature measurement result is equal to or more than the temperatureT8.

Preferably, upon the production of the composite ultrasound image in thediagnostic apparatus body, the ultrasound probe performs ultrasoundtransmission and reception for obtaining a main image as an ultrasoundimage in a preset predetermined output region by one of the plurality oftypes of ultrasound transmission and reception and an ultrasound imageobtained by the ultrasound transmission and reception for the main imagehas the normal depth.

The ultrasound probe preferably transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.

A second aspect of the invention provides an ultrasound diagnosticapparatus comprising:

an ultrasound probe configured to transmit ultrasonic waves into asubject and receive ultrasonic echoes generated by reflection of theultrasonic waves from the subject; and

a diagnostic apparatus body configured to generate ultrasound images inaccordance with the reception signals processed in the signal processorof said ultrasound probe,

wherein said ultrasound probe is configured to perform a plurality oftypes of ultrasound transmission and in mutually different directions ofultrasound transmission and reception and said diagnostic apparatus bodyis configured to combine ultrasound images based on each of theplurality of types of ultrasound transmission and reception, and

wherein said ultrasound probe configured to perform said plurality oftypes of ultrasound transmission and reception so as to transmit andreceive the ultrasonic waves in identical directions in a lastultrasound image of one composite ultrasound image and a firstultrasound image of its temporally adjacent composite ultrasound image.

In the ultrasound diagnostic apparatus according to the second aspect ofthe invention, the probe preferably further comprises a transmissioncontroller for controlling transmission of the ultrasonic waves from thepiezoelectric unit and a signal processor for processing the receptionsignals outputted from the piezoelectric unit.

At least one of the diagnostic apparatus body and the ultrasound probepreferably includes a selector for selecting a number of ultrasoundimages to be combined to produce the composite ultrasound image.

At least one of a predetermined number of temporally consecutivecomposite ultrasound images preferably has a different number ofultrasound images to be combined.

At least one of a predetermined number of temporally consecutivecomposite ultrasound images preferably has a different combination oftypes of ultrasound transmission and reception in ultrasound images.

An ultrasound image to be combined is preferably shared between thetemporally adjacent composite ultrasound images so that a lastultrasound image in one composite ultrasound image and a firstultrasound image in its subsequent composite ultrasound image transmitand receive the ultrasonic waves in the identical directions.

According to the first aspect of the inventive ultrasound diagnosticapparatus configured as described above, the ultrasound transmission andreception are changed depending on the temperature increase in theultrasound probe upon spatial compounding for combining a plurality ofimages different in the directions of ultrasound transmission andreception. More specifically, the number of images to be combined byspatial compounding is reduced depending on the temperature increase inthe ultrasound probe. Alternatively, the image quality of images becombined by spatial compounding is changed depending on the temperatureincrease in the ultrasound probe. Alternatively, the depth of images tobe combined by spatial compounding is changed depending on thetemperature increase in the ultrasound probe. Alternatively, dependingon the temperature increase of the ultrasound probe, the number of soundrays is changed beyond the predetermined depth in images to be combinedby spatial compounding and the areas having no sound rays areinterpolated upon the composition.

Therefore, according to the ultrasound diagnostic apparatus in the firstaspect of the invention, the drive frequency, drive time andtransmission/reception processing frequency of the piezoelectric unitand the integrated circuits such as AFEs for processing receptionsignals which are mounted on the ultrasound probe can be reduceddepending on the internal temperature of the ultrasound probe.Therefore, when heat is generated within the ultrasound probe, thetemperature increase in the integrated circuit and the piezoelectricunit can be suppressed. Heat generation from the ultrasound probe canalso be suppressed to minimize the deterioration of the image quality.

Therefore, the ultrasound diagnostic apparatus according to the firstaspect of the invention is capable of consistently obtaininghigh-definition ultrasound images through spatial compounding.

According to the ultrasound diagnostic apparatus in the second aspect ofthe invention, the frequency of the switching in the directions ofultrasound transmission and reception can be reduced also upon spatialcompounding.

Therefore, the ultrasound diagnostic apparatus according to the secondaspect of the invention is capable of simplifying the control ofultrasound transmission and reception upon spatial compounding.Accordingly, the burden of the ultrasound probe upon spatial compoundingcan be reduced, for example, in the ultrasound diagnostic apparatus inwhich the function of controlling the ultrasound transmission andreception is incorporated in the ultrasound probe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual block diagram showing the first embodiment of theultrasound diagnostic apparatus according to the first aspect of theinvention.

FIG. 2 is a conceptual diagram for illustrating spatial compounding thatmay be performed in the ultrasound diagnostic apparatus of theinvention.

FIGS. 3A, 3B and 3C are conceptual diagrams for illustrating an exampleof spatial compounding which is performed in the first embodiment of theultrasound diagnostic apparatus according to the first aspect of theinvention.

FIGS. 4A, 4B and 4C are conceptual diagrams for illustrating anotherexample of spatial compounding which is performed in the firstembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 5A and 5B are conceptual diagrams for illustrating yet anotherexample of spatial compounding which is performed in the firstembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIG. 6 is a conceptual block diagram showing the second embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

FIGS. 7A, 7B and 7C are conceptual diagrams for illustrating an exampleof spatial compounding which is performed in the second embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

FIGS. 8A, 8B and 8C are conceptual diagrams for illustrating anotherexample of spatial compounding which is performed in the secondembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 9A, 9B and 9C are conceptual diagrams for illustrating yet anotherexample of spatial compounding which is performed in the secondembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 10A, 10B and 10C are conceptual diagrams for illustrating stillanother example of spatial compounding which is performed in the secondembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIG. 11 is a conceptual block diagram showing the third embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

FIG. 12 is a conceptual diagram for illustrating reception signalprocessing through spatial compounding which is performed in the thirdembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 13A, 13B and 13C are conceptual diagrams for illustratingreception signal processing through spatial compounding which isperformed in the third embodiment of the ultrasound diagnostic apparatusaccording to the first aspect of the invention.

FIGS. 14A, 14B and 14C are conceptual diagrams for illustrating anexample of spatial compounding which is performed in the thirdembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 15A, 15B, 15C, 15D and 15E are conceptual diagrams forillustrating another example of spatial compounding which is performedin the third embodiment of the ultrasound diagnostic apparatus accordingto the first aspect of the invention.

FIGS. 16A, 16B and 16C are conceptual diagrams for illustrating yetanother example of spatial compounding which is performed in the thirdembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 17A, 17B, 17C, 17D and 17E are conceptual diagrams forillustrating still another example of spatial compounding which isperformed in the third embodiment of the ultrasound diagnostic apparatusaccording to the first aspect of the invention.

FIGS. 18A, 18B and 18C are conceptual diagrams for illustrating stillyet another example of spatial compounding which is performed in thethird embodiment of the ultrasound diagnostic apparatus according to thefirst aspect of the invention.

FIGS. 19A, 19B and 19C are conceptual diagrams for illustrating afurther example of spatial compounding which is performed in the thirdembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIG. 20 is a conceptual block diagram showing the fourth embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

FIGS. 21A, 21B and 21C are conceptual diagrams for illustrating soundray reduction through spatial compounding which is performed in thefourth embodiment of the ultrasound diagnostic apparatus according tothe first aspect of the invention.

FIGS. 22A, 22B and 22C are conceptual diagrams for illustrating soundray reduction through spatial compounding which is performed in thefourth embodiment of the ultrasound diagnostic apparatus according tothe first aspect of the invention.

FIGS. 23A, 23B and 23C are conceptual diagrams for illustrating anexample of spatial compounding which is performed in the fourthembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 24A, 24B and 24C are conceptual diagrams for illustrating anotherexample of spatial compounding which is performed in the fourthembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 25A, 25B and 25C are conceptual diagrams for illustrating yetanother example of spatial compounding which is performed in the fourthembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 26A, 26B and 26C are conceptual diagrams for illustrating stillanother example of spatial compounding which is performed in the fourthembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIGS. 27A, 27B and 27C are conceptual diagrams for illustrating stillyet another example of spatial compounding which is performed in thefourth embodiment of the ultrasound diagnostic apparatus according tothe first aspect of the invention.

FIGS. 28A, 28B and 28C are conceptual diagrams for illustrating afurther example of spatial compounding which is performed in the fourthembodiment of the ultrasound diagnostic apparatus according to the firstaspect of the invention.

FIG. 29 is a conceptual block diagram showing the ultrasound diagnosticapparatus according to the second aspect of the invention.

FIGS. 30A and 30B are conceptual diagrams for illustrating an example ofspatial compounding which is performed in the ultrasound diagnosticapparatus according to the second aspect of the invention. FIG. 30C is aconceptual diagram for illustrating normal spatial compounding.

FIGS. 31A and 31B are conceptual diagrams for illustrating anotherexample of spatial compounding which is performed in the ultrasounddiagnostic apparatus according to the second aspect of the invention.

FIGS. 32A and 32B are conceptual diagrams for illustrating yet anotherexample of spatial compounding which is performed in the ultrasounddiagnostic apparatus according to the second aspect of the invention.

FIGS. 33A and 33B are conceptual diagrams for illustrating still anotherexample of spatial compounding which is performed in the ultrasounddiagnostic apparatus according to the second aspect of the invention.

FIG. 34 is a conceptual diagram for illustrating spatial compounding.

DETAILED DESCRIPTION OF THE INVENTION

Next, the ultrasound diagnostic apparatus of the invention is describedin detail by referring to the preferred embodiments shown in theaccompanying drawings.

FIG. 1 is a conceptual block diagram showing the first embodiment of theultrasound diagnostic apparatus according to the first aspect of theinvention.

An ultrasound diagnostic apparatus 10A shown in FIG. 1 includes anultrasound probe 12A and a diagnostic apparatus body 14A. The ultrasoundprobe 12A is connected to the diagnostic apparatus body 14A by wirelesscommunication.

The ultrasound probe 12A (hereinafter referred to as “probe 12A”)transmits ultrasonic waves to a subject, receives ultrasonic echoesgenerated by reflection of the ultrasound waves on the subject, andoutputs reception signals of an ultrasound image in accordance with thereceived ultrasonic echoes.

In the practice of the invention, various known ultrasound probes can beused for the probe 12A. Therefore, there is no particular limitation onthe type of the probe 12A and various types such as convex type, lineartype and sector-type can used. The probe may be an external probe or aradial scan type probe for use in an ultrasound endoscope. In addition,the probe 12A may have ultrasound transducers compatible with harmonicimaging for use in receiving second or higher order harmonics fromtransmitted ultrasonic waves.

The probe 12A includes a piezoelectric unit 16, a signal processor 20, aparallel/serial converter 24, a wireless communication unit 26, anantenna 28, a transmission drive 30, a transmission controller 32A, areception controller 34A, a communication controller 36, a probecontroller 38 and a temperature sensor 42.

The piezoelectric unit 16 is a one-dimensional or two-dimensional arrayof (ultrasound) transducers 18 transmitting and receiving ultrasonicwaves. The piezoelectric unit 16 is connected to the signal processor20.

The signal processor 20 includes individual signal processors 20 acorresponding to the individual transducers 18 of the piezoelectric unit16. The individual signal processors 20 a are connected to the wirelesscommunication unit 26 via the parallel/serial converter 24. The wirelesscommunication unit 26 is further, connected to the antenna 28.

Each of the transducers 18 is connected to the transmission controller32A via the transmission drive 30. Each of the individual signalprocessors 20 a is connected to the reception controller 34A. Thewireless communication unit 26 is connected to the communicationcontroller 36.

The parallel/serial converter 24, the transmission controller 32A, thereception controller 34A, and the communication controller 36 areconnected to the probe controller 38.

The probe 12A of the ultrasound diagnostic apparatus 10A is providedwith the temperature sensor 42 for measuring the temperature of thesignal processor 20. The temperature measurement result obtained withthe temperature sensor 42 is supplied to the transmission controller 32Aand the reception controller 34A.

The probe 12A includes a built-in battery, which supplies electric powerfor drive to each component. The battery is not shown in FIG. 1.

The piezoelectric unit 16 is of a known type which includes aone-dimensional or two-dimensional array of the transducers 18transmitting and receiving ultrasonic waves, and a backing layer, anacoustic matching layer and an acoustic lens laminated thereon.

Each of the transducers 18 is an ultrasound transducer having apiezoelectric body made of, for example, PZT (lead zirconate titanate)or PVDF (polyvinylidene fluoride), and electrodes provided on both endsof the piezoelectric body.

When a pulsed voltage or a continuous-wave voltage is applied to theelectrodes of the ultrasound transducer, the piezoelectric body expandsand contracts to cause the transducer to generate pulsed or continuousultrasonic waves. The ultrasonic waves generated by the ultrasoundtransducers are combined to form ultrasonic beams.

Upon reception of propagating ultrasonic waves, each ultrasoundtransducer expands and contracts to produce electric signals, which arethen outputted as ultrasonic reception signals.

The transducers 18 transmit ultrasonic waves according to drive signalssupplied from the transmission drive 30. The transducers 18 receiveultrasonic echoes from the subject, convert the received ultrasonicechoes into electric signals (reception signals) and output the electricsignals to the individual signal processors 20 a.

The transmission drive 30 includes a digital/analog converter, alow-pass filter, an amplifier and pulsers. The transmission drive 30supplies each transducer 18 (electrodes of the ultrasound transducer)with a pulsed drive voltage (transmission pulse) to oscillate theultrasound transducer to thereby transmit ultrasonic waves.

The transmission drive 30 adjusts the delay amounts of drive signals forthe respective transducers 18 based on a transmission delay patternselected by the transmission controller 32A and supplies the transducers18 with adjusted drive signals so that the ultrasonic waves transmittedfrom the transducers 18 form ultrasonic beams.

The transducers 18 of the piezoelectric unit 16 are connected to thecorresponding individual signal processors 20 a of the signal processor20.

Each individual signal processor 20 a has an AFE (analog front end)including an LNA (low-noise amplifier), a VCA (voltage-controlledattenuator), a PGA (programmable gain amplifier), a low-pass filter andan analog/digital converter. Under the control of the receptioncontroller 34A, the individual signal processors 20 a convert thereception signals outputted from the corresponding transducers 18 intodigital reception signals in the AFE. Then, the individual signalprocessors 20 a subject the digital reception signals generated in theAFE to quadrature detection or quadrature sampling to generate complexbaseband signals. In addition, the individual signal processors 20 asample the generated complex baseband signals to generate sample datacontaining tissue area information and supply the generated sample datato the parallel/serial converter 24.

The parallel/serial converter 24 converts the parallel sample datagenerated by the individual signal processors 20 a in a plurality ofchannels into serial sample data.

The probe 12A is provided with the temperature sensor 42 for measuringthe temperature of the signal processor 20 (reception signal processingcircuit portion). The temperature measurement result of the signalprocessor 20 obtained with the temperature sensor 42 is sent to thetransmission controller 32A and the reception controller 34A.

The temperature sensor 42 is not particularly limited but knowntemperature sensors can be used.

The use of the temperature sensor 42 is not limited to the measurementof the temperature of the signal processor 20 but the internaltemperature of the probe 12A may be measured. However, the temperaturesensor 42 preferably measures the temperature of the signal processor 20because heat generation from the signal processor 20 (in particular theAFEs) which processes the reception signals outputted from thetransducers 18 is the largest in the probe 12A.

The ultrasound diagnostic apparatus 10A has the function of spatialcompounding in which ultrasound images obtained by the ultrasoundtransmission and reception (transmission and reception of an ultrasonicwave) in mutually different directions are combined to produce acomposite ultrasound image. In the illustrated case, for example, threeultrasound images are combined in spatial compounding. Therefore, whenspatial compounding is performed, the transmission controller 32A andthe reception controller 34A control the drive of the transmission drive30 and the individual signal processors 20 a, respectively, such thatthree types of ultrasound transmission and reception are performed inthree mutually different directions of transmission and reception.

In the ultrasound diagnostic apparatus 10A, the number of images to becombined by spatial compounding is changed depending on the temperatureat a predetermined position inside the probe 12A. More specifically, thereception controller 34A and the transmission controller 32A change thenumber of types of ultrasound transmission and reception depending onthe temperature of the signal processor 20 measured with the temperaturesensor 42 so as to change the number of ultrasound images to besubjected to spatial compounding. This point will be described in detaillater.

The wireless communication unit 26 performs carrier modulation based onthe serial sample data to generate transmission signals. The wirelesscommunication unit 26 supplies the antenna 28 with the generatedtransmission signals so that the antenna 28 transmits radio waves toachieve transmission of the serial sample data.

The modulation methods that may be employed herein include ASK(Amplitude Shift Keying), PSK (Phase Shift Keying), QPSK (QuadraturePhase Shift Keying), and 16QAM (16 Quadrature Amplitude Modulation).

The wireless communication unit 26 uses the antenna 28 to transmit thesample data to the diagnostic apparatus body 14A through wirelesscommunication with the diagnostic apparatus body 14A. In addition, thewireless communication unit 26 receives various control signals from thediagnostic apparatus body 14A and outputs the received control signalsto the communication controller 36.

The communication controller 36 controls the wireless communication unit26 so that the sample data is transmitted at a transmission radio fieldintensity that is set by the probe controller 38. The communicationcontroller 36 outputs the various control signals received by thewireless communication unit 26 to the probe controller 38.

The probe controller 38 controls various components of the probe 12Aaccording to various control signals transmitted from the diagnosticapparatus body 14A.

As described above, the ultrasound diagnostic apparatus 10A of theinvention has the function of producing an image (composite ultrasoundimage) through spatial compounding.

As is well known, spatial compounding is a technique which involvesperforming a plurality of types of ultrasound transmission and receptionwith respect to a subject in mutually different directions of ultrasoundtransmission and reception (at mutually different scanning angles or inmutually different scanning directions), and combining ultrasound imagesobtained by the plurality of types of ultrasound transmission andreception to produce a composite ultrasound image. Such spatialcompounding enables speckle of ultrasound images to be reduced.

When spatial compounding is performed in the illustrated ultrasounddiagnostic apparatus 10A, the probe 12A performs the three types ofultrasound transmission and reception in mutually different directions.As conceptually shown in FIG. 2, the three types of transmission andreception include, for example, transmission and reception for obtaininga main image (ultrasound image covering the whole area for outputting asa composite ultrasound image) which is an ultrasound image having thesame region as that of a normal ultrasound image (this case ishereinafter referred to as the “transmission and reception for the mainimage”), ultrasound transmission and reception in a direction inclinedby an angle of θ with respect to the direction of the ultrasoundtransmission and reception for the main image (ultrasound transmissionand reception in the direction inclined by the angle of θ″), andultrasound transmission and reception in a direction inclined by anangle of −θ with respect to the direction of the transmission andreception for the main image.

For convenience, the transmission and reception for the main image isalso referred to as the “transmission and reception for an image A”, theultrasound transmission and reception in the direction inclined by theangle of θ with respect to the direction of the transmission andreception for the image A to as the “transmission and reception for animage B”, and the ultrasound transmission and reception in the directioninclined by the angle of −θ with respect to the direction of thetransmission and reception for the image A to as the “transmission andreception for an image C.”

When spatial compounding is performed, the transmission controller 32Aand the reception controller 34A control the drive of the transmissiondrive 30 and the individual signal processors 20 a, respectively, suchthat the transmission and reception for the images A, B and C areperformed in a predetermined order.

In other words, when spatial compounding is performed in the illustratedexample, the three types of ultrasound transmission and reception whichmake up a frame unit for obtaining a composite ultrasound image arerepeatedly performed on a frame basis without changing the frame rate.

Therefore, when spatial compounding is performed, the transmissioncontroller 32A and the reception controller 34A of the probe 12A controlthe drive of the transmission drive 30 and the individual signalprocessors 20 a, respectively, such that the three types of ultrasoundtransmission and reception are repeatedly performed.

When spatial compounding is performed, the diagnostic apparatus body 14A(more specifically an image combining unit 80) combines the threeultrasound images including the ultrasound image A (solid line) obtainedby the transmission and reception for the image A, the ultrasound imageB (broken line) obtained by the transmission and reception for the imageB, and the ultrasound image C (chain line) obtained by the transmissionand reception for the image C to produce a composite ultrasound imagecovering the region of the ultrasound image A.

Therefore, in the illustrated example, the number (predetermined number)of ultrasound images to be combined by spatial compounding is three.

In the practice of the invention, the predetermined number of ultrasoundimages to be combined by spatial compounding is not limited to three butmay be two or four or more.

The method of ultrasound transmission and reception in differentdirections is not limited to the method as conceptually shown in FIG. 2in which the ultrasound transmission and reception are delayed. Variousknown methods of ultrasound transmission and reception in differentdirections can be used, as exemplified by the methods described in JP2005-58321 A and JP 2003-70786 A.

In addition, the illustrated example refers to the linear type but, asdescribed above, the invention is applicable to probes of various typesincluding convex type and sector type.

As described above, the probe 16 is provided with the temperature sensor42 for measuring the temperature of the signal processor 20. Thetemperature measurement result obtained with the temperature sensor 42is supplied to the transmission controller 32A and the receptioncontroller 34A.

The temperature thresholds including the first temperature T1 [° C.] andthe second temperature T2 [° C.] which is higher than T1 are set for theprobe 12A (the transmission controller 32A and the reception controller34A). In the ultrasound diagnostic apparatus 10A, T1 and T2 may be fixedor variable if the relation of T1<T2 is met.

When the temperature measurement result obtained with the temperaturesensor 42 is less than T1 upon spatial compounding, the three types ofultrasound transmission and reception (corresponding to three ultrasoundimages) are all performed in one frame. In other words, the three typesof ultrasound transmission and reception are all performed when theprobe 12A (signal processor 20) has a steady temperature.

For example, the transmission controller 32A and the receptioncontroller 34A first perform the transmission and reception for theimage A for obtaining the ultrasound image A serving as the main image.

Then, the transmission controller 32A and the reception controller 34Aperform the transmission and reception for the image B for obtaining theultrasound image B in the direction inclined by the angle of θ withrespect to the direction for the ultrasound image A.

Then, the transmission controller 32A and the reception controller 34Aperform the transmission and reception for the image C for obtaining theultrasound image C in the direction inclined by the angle of −θ withrespect to the direction for the ultrasound image A.

More specifically, when the temperature measurement result obtained withthe temperature sensor 42 is less than T1, as conceptually shown in FIG.3A, the probe 12A performs, in one frame, all of the three types ofultrasound transmission and reception including the “transmission andreception for the image A”, the “transmission and reception for theimage B” and the “transmission and reception for the image C”.Therefore, the ultrasound transmission and reception are performed forthree images. The diagnostic apparatus body 14A combines the threeultrasound images obtained in one frame to produce a compositeultrasound image.

In contrast, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T1 but less than T2, theprobe 12A reduces, in one frame, the number of times of ultrasoundtransmission and reception for producing the composite ultrasound imageby 1 corresponding to the formation of one image, thus performing theultrasound transmission and reception for two images not for one image(non-operational periods are provided). In other words, when thetemperature is equal to or more than T1 but less than T2, one type ofultrasound transmission and reception is reduced from the three types ofultrasound transmission and reception to perform two types of ultrasoundtransmission and reception.

For example, when the temperature measurement result is equal to or morethan T1 but less than T2, the probe 12A first performs, in one frame,the transmission and reception for the image A, then the transmissionand reception for the image B, and does not perform the transmission andreception for the subsequent image C.

More specifically, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T1 but less than T2,as conceptually shown in FIG. 3B, the ultrasound transmission andreception are repeatedly performed on a frame basis according to theprocess of one frame including the “transmission and reception for theimage A”, “transmission and reception for the image B” and“non-operation (stop).” The diagnostic apparatus body 14A combines twoultrasound images obtained in one frame to produce a compositeultrasound image.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T2, the probe 12A reduces the numberof times of ultrasound transmission and reception for producing thecomposite ultrasound image by 2 corresponding to the formation of twoimages, thus performing the ultrasound transmission and reception forone image not for two images (non-operational periods are prolonged). Inother words, when the temperature is equal to or more than T2, two typesof ultrasound transmission and reception are reduced from the threetypes of ultrasound transmission and reception to perform only one typeof ultrasound transmission and reception.

For example, when the temperature measurement result is equal to or morethan T2, the probe 12A first performs, in one frame, the transmissionand reception for the image A but does not perform the transmission andreception for the image B and also the transmission and reception forthe subsequent image C.

More specifically, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T2, as conceptuallyshown in FIG. 3C, the ultrasound transmission and reception arerepeatedly performed on a frame basis according to the process of oneframe including the “transmission and reception for the image A”,“non-operation” and “non-operation.” The diagnostic apparatus body 14Auses one ultrasound image obtained in one frame to produce a compositeultrasound image. In other words, when the temperature measurementresult obtained with the temperature sensor 42 is equal to or more thanT2, spatial compounding is not performed in the ultrasound diagnosticapparatus 10A.

As is clear from the above description, in cases where the temperatureof the probe 12A is increased upon spatial compounding, the ultrasounddiagnostic apparatus 10A reduces the drive time of the signal processor20 and the like without changing the frame rate for producing compositeultrasound images through spatial compounding. In other words, in caseswhere the temperature of the probe 12A is increased, the drive of thesignal processor 20 and other heat generation part stopped depending onthe temperature.

Therefore, according to the invention, the internal temperature of theprobe 12A can be promptly reduced by stopping the heat generation partsuch as the signal processor 20 even if the temperature of the probe 12Ais increased upon spatial compounding. Even if the temperature of theprobe 12A is increased, the image quality deterioration can be minimizedby promptly reducing the temperature inside the probe 12A whilesuppressing the temperature increase therein.

In the example shown in FIGS. 3A to 3C, the order of ultrasoundtransmission and reception of the images of one frame is the same forall the frames but this is not the sole case of the invention. In otherwords, the order of ultrasound transmission and reception of the imagesin each frame may be different. In addition, the order of ultrasoundtransmission and reception of the images of one frame may be differentbetween cases where the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T1 but less than T2 andcases where the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T2.

Examples of these processes are shown in FIGS. 4A-4C and 5A-5B.

For example, when the temperature measurement result obtained with thetemperature sensor 42 is less than T1, as shown in FIG. 4A, theultrasound transmission and reception of the first frame, the secondframe, the third frame and the like may be performed in the orders of“image A→image B→image C”, “image C→image B→image A”, “image A→imageB→image C” and the like, respectively.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T1 but less than T2 and theultrasound transmission and reception are not performed for the image C,as shown in FIG. 4B, the ultrasound transmission and reception of thefirst frame, the second frame, the third frame and the like may beperformed in the orders of “image A→image B→non-operation (stop)”,“image B→image A→non-operation”, “image A→image B→non-operation” and thelike, respectively.

That is, in the practice of the invention, the directions of ultrasoundtransmission and reception in the last ultrasound image in one of twoconsecutive frames (i.e., two temporally consecutive compositeultrasound images) and the first ultrasound image in the subsequentframe may be the same.

This order of ultrasound transmission and reception enables theultrasound transmission and reception to be continued in the samedirections to facilitate the control of the transmission drive 30 andthe individual signal processors 20 a.

For example, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T1 but less than T2 andthe ultrasound transmission and reception are not performed for theimage C, as shown in FIG. 4C, the non-operational time period may beincreased by continuing the non-operational state provided in the lastpart of one frame up to the first part of the subsequent frame, morespecifically by performing the ultrasound transmission and reception ofthe first frame, the second frame, the third frame and the like in theorders of “image A→image B→non-operation (stop)”, “non-operation imageB→image A”, “image A→image B→non-operation” and the like, respectively.

In the above examples, the number of non-operational states determinedby the temperature measurement results is the same in all the frames butthis is not the sole case of the invention. That is, the number ofnon-operational states may be different in the consecutive frames. Inother words, in the practice of the invention, in cases where thetemperature of the probe 12A is increased, the ultrasound transmissionand reception may be stopped anywhere within two consecutive frames.

For example, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T1 but less than T2, asshown in FIG. 5A, the ultrasound transmission and reception of the firstframe, the second frame, the third frame, the fourth frame and the likemay be performed in the orders of “image B→image A→image C”, “imageC→image A→non-operation (stop)”, “image A→image B→non-operation”, “imageB→image A→image C” and the like, respectively.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T2, as shown in FIG. 5B, theultrasound transmission and reception of the first frame, the secondframe, the third frame, the fourth frame and the like may be performedin the orders of “image B→image A→non-operation”, “non-operation→imageA→non-operation”, “non-operation→image A→non-operation”, “image A→imageB→non-operation” and the like, respectively.

In the example shown in FIGS. 5A and 5B, similarly to the example shownin FIGS. 4A to 4C, the directions of ultrasound transmission andreception are the same in the last ultrasound image in one frame and thefirst ultrasound image in its subsequent frame. However, in the exampleshown in FIGS. 5A and 5B in which the number of ultrasound images to becombined is different in the consecutive frames, this is not the solecase of the invention. That is, even in the example shown in FIGS. 5Aand 5B in which the number of ultrasound images to be combined isdifferent in the consecutive frames, the directions of ultrasoundtransmission and reception may be different between the last ultrasoundimage in one frame and the first ultrasound image in its subsequentframe as in the example shown in FIG. 3A.

In the above examples, the transmission and reception for the image Band/or the transmission and reception for the image C are stopped whenthe temperature inside the probe 12A is increased but this is not thesole case of the invention. That is, the transmission and reception forthe image A ma stopped as a result of a temperature increase and acomposite ultrasound image in the region of the ultrasound image A beproduced from the transmission and reception for the image B and thetransmission and reception for the image C.

However, the composite ultrasound image produced in the diagnosticapparatus body 14A is an image having the region of the ultrasound imageA serving as the main image. Therefore, it is more advantageous toperform the transmission and reception for the image A serving as themain image (transmission and reception covering the whole area foroutputting as a composite ultrasound image) because a proper compositeultrasound image can be consistently obtained. In cases where theultrasound transmission and reception are performed only for one imagebecause of the temperature increase, the transmission and reception forthe image A which is the normal ultrasound transmission and reception isto be performed to output an ultrasound image in a predetermined region.

In addition, in the above examples, since the predetermined number(maximum number of images to be combined) upon spatial compounding isthree, two temperature thresholds are provided but this is not the solecase of the invention. For example, in cases where the predeterminednumber upon spatial compounding is four or more, three or morethresholds may be provided.

Even if the predetermined number is four or more and/or the number ofthresholds is three or more, the example shown in FIGS. 4A-4C in whichthe order of ultrasound transmission and reception of the images isdifferent in consecutive frames and the example shown in FIGS. 5A and 5Bin which the number of times of ultrasound transmission and receptionperformed in consecutive frames is different are of course applicable.

As described above, the reception signals outputted from the probe 12Aare supplied to the diagnostic apparatus body 14A by wirelesscommunication.

The diagnostic apparatus body 14A includes an antenna 50, a wirelesscommunication unit 52, a serial/parallel converter 54, a data storageunit 56, an image generating unit 58, a display controller 62, a monitor64, a communication controller 68, an apparatus body controller 70 andan operating unit 72.

The antenna 50 for use in the transmission to and reception from theantenna 28 of the probe 12A is connected to the wireless communicationunit 52. The wireless communication unit 52 is connected to the datastorage unit 56 via the serial/parallel converter 54. The data storageunit 56 is connected to the image generating unit 58. The imagegenerating unit 58 is connected to the monitor 64 via the displaycontroller 62.

The wireless communication unit 52 is connected to the communicationcontroller 68. The serial/parallel converter 54, the image generatingunit 58, the display controller 62 and the communication controller 68are connected to the apparatus body controller 70.

The apparatus body controller 70 controls the components in thediagnostic apparatus body 14A. The apparatus body controller 70 isconnected to the operating unit 72 to perform various input operationsincluding as to whether or not spatial compounding is to be performed.

The diagnostic apparatus body 14A includes a built-in power supply unit,which supplies electric power for drive to each component. The powersupply unit is not shown in FIG. 1.

The diagnostic apparatus body 14A may include a recharging means forrecharging a built-in battery of the probe 12A.

The wireless communication unit 52 transmits various control signals tothe probe 12A through wireless communication with the probe 12A. Thewireless communication unit 52 demodulates the signals received by theantenna 50 to output serial sample data.

The communication controller 68 controls the wireless communication unit52 so that various control signals are transmitted at a transmissionradio field intensity that is set by the apparatus body controller 70.

The serial/parallel converter 54 converts the serial sample dataoutputted from the wireless communication unit 52 into parallel sampledata. The data storage unit 56 is constituted by a memory, a hard disk,or the like and stores at least one frame of sample data converted bythe serial/parallel converter 54.

The image generating unit 58 performs reception focusing on sample datafor each image read out from the data storage unit 56 to generate imagesignals representing an ultrasound image. The image generating unit 58includes a phase adjusting and summing unit 76, an image processor 78and the image combining unit 80.

The phase adjusting and summing unit 76 selects one reception delaypattern from a plurality of previously stored reception delay patternsaccording to the reception direction set by the apparatus bodycontroller 70 and, based on the selected reception delay pattern,provides the complex baseband signals represented by the sample datawith respective delays and adds them up to perform the receptionfocusing. This reception focusing yields baseband signals (sound raysignals) where the ultrasonic echoes are well focused.

The image processor 78 generates image signals for an ultrasound image(B-mode image), which is tomographic image information on a tissueinside the subject, according to the sound ray signals generated by thephase adjusting and summing unit 76.

The image processor 78 includes an STC (sensitivity time control)section and a DSC (digital scan converter). The STC section corrects thesound ray signals for the attenuation due to distance according to thedepth at which the ultrasonic waves are reflected. The DSC converts thesound ray signals corrected by the SIC into image signals compatiblewith the common scanning method of television signals (rasterconversion) and performs required image processing such as gradationprocessing to generate ultrasound image signals.

The image combining unit 80 combines the ultrasound images when spatialcompounding is performed.

The ultrasound diagnostic apparatus 10A basically combines threeultrasound images when spatial compounding is performed.

In the ultrasound diagnostic apparatus 10A, as described above, thetemperature of the reception processor 20 is measured with thetemperature sensor 42 and the number of ultrasound images to be combinedby spatial compounding is appropriately reduced while increasing thenon-operational time period of the reception processor 20 and the likeeach time the measured temperature exceeds one of the set temperaturethresholds.

For example, upon spatial compounding, the probe 12A performs thetransmission and reception for the image A, the transmission andreception for the image B and the transmission and reception for theimage C as shown in FIG. 3A when the temperature measurement resultobtained with the temperature sensor 42 shows that the temperature isless than T1.

When the temperature measured with the temperature sensor 42 is equal toor more than T1 but less than T2, as shown in FIG. 3B, the probe 12Aonly performs the transmission and reception for the image A and thetransmission and reception for the image B (the transmission andreception for the image C are not performed).

When the temperature measured with the temperature sensor 42 is equal toor more than T2, as shown in FIG. 3C, the probe 12A only performs thetransmission and reception for the image A (the transmission andreception for the images B and C are not performed).

When spatial compounding is performed in the respective cases, the imagecombining unit 80 combines three or two ultrasound images for which theultrasound transmission and reception were performed based on thetemperature of the reception processor 20 measured with the temperaturesensor 42 and there is no image composition when one ultrasound image isformed.

In the example shown in FIGS. 3A to 3C, when the temperature measuredwith the temperature sensor 42 is less than T1, the image combining unit80 combines the ultrasound image A derived from the transmission andreception for the image A, the ultrasound image B derived from thetransmission and reception for the image B, and the ultrasound image Cderived from the transmission and reception for the image C to generateimage signals for a composite ultrasound image.

When the temperature measured with the temperature sensor 42 is equal toor more than T1 but less than T2, the image combining unit 80 combinesthe ultrasound image A derived from the transmission and reception forthe image A and the ultrasound image B derived from the transmission andreception for the image B to generate image signals for a compositeultrasound image.

When the temperature measured with the temperature sensor 42 is equal toor more than T2, the ultrasound image A derived from the transmissionand reception for the image A is only supplied and therefore the imagecombining unit 80 does not perform image composition but directlyoutputs the image signals for the ultrasound image A as in theproduction of a normal ultrasound image.

The display controller 62 causes the monitor 64 to display theultrasound image according to the image signals generated by the imagegenerating unit 58.

The monitor 64 includes a display device such as an LCD, for example,and displays the ultrasound image under the control of the displaycontroller 62.

The operation of the ultrasound diagnostic apparatus 10A shown in FIG. 1is described below.

In the ultrasound diagnostic apparatus 10A, during the diagnosis,various kinds of information inputted from the operating unit 72 of thediagnostic apparatus body 14A are first sent from the wirelesscommunication unit 52 (antenna 50) of the diagnostic apparatus body 14Ato the wireless communication unit 26 (antenna 28) of the probe 12A andthen supplied to the probe controller 38. Then, ultrasonic waves aretransmitted from the transducers 18 in accordance with the drive voltagesupplied from the transmission drive 30 of the probe 12A.

The reception signals outputted from the transducers 18 that havereceived the ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject are supplied to the corresponding individual signalprocessors 20 a to generate sample data.

In the probe 12A, when spatial compounding is performed, the temperaturemeasurement result of the signal processor 20 obtained with thetemperature sensor 42 is sent to the transmission controller 32A and thereception controller 34A.

In the ultrasound diagnostic apparatus 10A, the number of ultrasoundimages to be combined by spatial compounding is appropriately reducedbased on the temperature measurement result each time the temperature ofthe reception processor 20 exceeds one of the set temperaturethresholds. Therefore, in the probe 12A, the number of ultrasound imagesfor which the ultrasound transmission and reception are to be performedis appropriately reduced while increasing the non-operational timeperiod of the reception processor 20 and the like based on thetemperature measurement result of the signal processor 20 obtained withthe temperature sensor 42.

For example, when the temperature measurement result obtained with thetemperature sensor 42 is less than T1, the transmission controller 32Aand the reception controller 34A control the operations of thetransmission drive 30 and the signal processor 20 (each individualsignal processor 20 a) so that the transmission and reception for theimage A, the transmission and reception for the image B and thetransmission and reception for the image C are performed as shown inFIG. 3A.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T1 but less than T2, the transmissioncontroller 32A and the reception controller 34A control the operationsof the transmission drive 30 and the signal processor 20 so that thetransmission and reception for the image A and the transmission andreception for the image B are performed but the transmission andreception for the image C are stopped as shown in FIG. 3B.

When the temperature measured with the temperature sensor 42 is equal toor more than T2, the transmission controller 32A and the receptioncontroller 34A control the operations of the transmission drive 30 andthe signal processor 20 so that the transmission and reception for theimage A are only performed and the transmission and reception for theimage B and the transmission and reception for the image C are stoppedas shown in FIG. 3C.

The sample data generated by the individual signal processors 20 a aresent to the parallel/serial converter 24, where the sample data isconverted into serial data. The serial data is then wirelesslytransmitted from the wireless communication unit 26 (antenna 28) to thediagnostic apparatus body 14A.

The sample data received by the antenna 50 of the diagnostic apparatusbody 14A is sent to the wireless communication unit 52. The sample datais then sent from the wireless communication unit 52 to theserial/parallel converter 54 and is converted into parallel data. Thesample data converted into parallel form is stored in the data storageunit 56.

Further, the sample data for each image is read out from the datastorage unit 56 to generate image signals of an ultrasound image in theimage generating unit 58. The display controller 62 causes the monitor64 to display the ultrasound image based on the image signals.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 combines the ultrasound images.

In the ultrasound diagnostic apparatus 10A, as described above, thenumber of ultrasound images to be combined by spatial compounding isappropriately reduced each time the temperature of the receptionprocessor 20 exceeds one of the set temperature thresholds. Based on thetemperature of the reception processor 20, the image combining unit 80combines three or two images or does not perform image composition whenone ultrasound image is formed.

More specifically, in the example shown in FIG. 3A to 3C, when thetemperature measured with the temperature sensor 42 in the probe 12A isless than T1, the image combining unit 80 combines the ultrasound imageA derived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image, and outputs the image signals to the displaycontroller 62.

When the temperature measured with the temperature sensor 42 in theprobe 12A is equal to or more than T1 but less than T2, the imagecombining unit 80 combines the ultrasound image A derived from thetransmission and reception for the image A and the ultrasound image Bderived from the transmission and reception for the image B to generateimage signals for a composite ultrasound image, and outputs the imagesignals to the display controller 62.

When the temperature measured with the temperature sensor 42 in theprobe 12A is equal to or more than T2, the image combining unit 80 doesnot perform image composition but directly outputs the image signals ofthe ultrasound image A to the display controller 62.

FIG. 6 is a conceptual block diagram showing the second embodiment orthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

Many components of the ultrasound diagnostic apparatus 10B shown in FIG.6 are the same as those of the ultrasound diagnostic apparatus 10A shownin FIG. 1. Therefore, like components are denoted by the same referencenumerals and the following description mainly focuses on the differentfeatures.

As in the first embodiment of the ultrasound diagnostic apparatus 10A,the ultrasound diagnostic apparatus 10B shown in FIG. 6 includes anultrasound probe 12B (hereinafter referred to as “probe 12B”) and adiagnostic apparatus body 14B. As in the above embodiment, theultrasound probe 12B is connected to the diagnostic apparatus body 14Bby wireless communication.

Similarly to the probe 12A in the first embodiment, the probe 12Btransmits ultrasonic waves to the subject, receives ultrasonic echoesgenerated by reflection of the ultrasound waves on the subject, andoutputs reception signals of an ultrasound image in accordance with thereceived ultrasonic echoes.

There is no limitation on the type of the probe 12B and various knownultrasound probes can be used.

As in the probe 12A, the probe 12B also includes a piezoelectric unit16, a signal processor 20, a parallel/serial converter 24, a wirelesscommunication unit 26, an antenna 28, a transmission drive 30, atransmission controller 32B, a reception controller 34B, a communicationcontroller 36, a probe controller 38 and a temperature sensor 42.

The probe 12B also includes a built-in battery (not shown), whichsupplies electric power for drive to each component.

The piezoelectric unit 16, the signal processor 20, the parallel/serialconverter 24, the wireless communication unit 26, the antenna 28, thetransmission drive 30, the communication controller 36, the probecontroller 38 and the temperature sensor 42 are basically the same asthose of the probe 12A.

More specifically, the piezoelectric unit 16 is a one-dimensional ortwo-dimensional array of transducers 18 transmitting and receivingultrasonic waves.

The transmission drive 30 supplies the transducers 18 with a drivevoltage so that the transducers transmit ultrasonic waves so as to formultrasonic beams.

The transducers 18 output the reception signals of the ultrasonic echoesto individual signal processors 20 a of the signal processor 20. Asdescribed above, each individual signal processor 20 a has an AFE,processes the reception signals to generate sample data and supplies thegenerated sample data the parallel/serial converter 24. Theparallel/serial converter 24 converts the parallel sample data intoserial sample data.

The ultrasound diagnostic apparatus 10B also has the function of spatialcompounding in which ultrasound images obtained by the ultrasoundtransmission and reception in mutually different directions are combinedto produce a composite ultrasound image.

Similarly to the above ultrasound diagnostic apparatus 10A, theultrasound diagnostic apparatus 10B combines, for example, threeultrasound images upon spatial compounding. Therefore, the transmissioncontroller 32B and the reception controller 34B control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, such that three types of ultrasound transmission andreception are performed in mutually different directions of ultrasoundtransmission and reception.

The probe 12B has the temperature sensor 42 for measuring thetemperature of the signal processor 20. The temperature sensor 42supplies the temperature measurement result to the transmissioncontroller 32B and the reception controller 34B.

Upon spatial compounding, the transmission controller 32B and thereception controller 34B change the image quality of the ultrasoundimages for use in producing the composite ultrasound image based on thetemperature measurement result. More specifically, based on thetemperature of the signal processor 20 measured with the temperaturesensor 42, the transmission controller 32B and the reception controller34B control the drive of the transmission drive 30 and the individualsignal processors 20 a, respectively so as to change the number of soundrays and/or the number of available channels in the ultrasoundtransmission and reception for the predetermined ultrasound images to besubjected to spatial compounding.

This point will be described in detail later.

The wireless communication unit 26 generates transmission signals fromthe serial sample data and transmits the serial sample data to thediagnostic apparatus body 14B via the antenna 28.

The wireless communication unit 26 receives various control signals fromthe diagnostic apparatus body 14B and outputs the received controlsignals to the communication controller 36.

The communication controller 36 controls the wireless communication unit26. The communication controller 36 outputs the various control signalsreceived by the wireless communication unit 26 to the probe controller38.

The probe controller 38 controls various components of the probe 12Baccording to various control signals transmitted from the diagnosticapparatus body 14B.

As described above, the ultrasound diagnostic apparatus 10B has thefunction of producing an image (composite ultrasound image) throughspatial compounding.

As in the first embodiment of the ultrasound diagnostic apparatus 10Ashown in FIG. 1, the ultrasound diagnostic apparatus 10B also performs,for example, the three types of ultrasound transmission and reception inmutually different directions upon spatial compounding as conceptuallyshown in FIG. 2. More specifically, upon spatial compounding, the probe12B performs the three types of ultrasound transmission and reception,including the “transmission and reception for the image A” as theultrasound transmission and reception for obtaining the main image(image including the whole area of the composite ultrasound image formedby spatial compounding), the “transmission and reception for the image3” in a direction inclined by an angle of θ with respect to thedirection of the transmission and reception for the image A, and the“transmission and reception for the image C” in a direction inclined byan angle of −θ with respect to the direction of the transmission andreception for the image A.

Also in this embodiment, when spatial compounding is performed, theprobe 12B repeatedly performs the three types of ultrasound transmissionand reception which make up a frame unit without changing the frame rate(see FIGS. 7A to 7C).

When spatial compounding is performed, the transmission controller 32Band the reception controller 34B of the probe 12B control the drive ofthe transmission drive 30 and the individual signal processors 20 a,respectively, such that the three types of ultrasound transmission andreception are repeatedly performed.

On the other hand, when spatial compounding is performed, the diagnosticapparatus body 14B (more specifically an image combining unit 80)combines the three ultrasound images including the ultrasound image A(solid line) as the main image obtained by the transmission andreception for the image A, the ultrasound image B (broken line) obtainedby the transmission and reception for the image B, and the ultrasoundimage C (chain line) obtained by the transmission and reception for theimage C to produce a composite ultrasound image covering the region ofthe ultrasound image A.

Therefore, the number (predetermined number) of ultrasound images to becombined by spatial compounding in the ultrasound diagnostic apparatus10B is three. However, the predetermined number may be two or four ormore as in the above embodiment.

In addition, various known methods can be used to transmit and receiveultrasonic waves in different directions as in the above embodiment.

As described above, the probe 12B is provided with the temperaturesensor 42 for measuring the temperature of the signal processor 20. Thetemperature measurement result obtained with the temperature sensor 42is supplied to the transmission controller 32B and the receptioncontroller 34B.

The temperature thresholds including the first temperature T3 [° C.] andthe second temperature T4 [° C.] which is higher than T3 are set for theprobe 12B (transmission controller 32B and the reception controller34B). In the ultrasound diagnostic apparatus 10B, 13 and T4 may be fixedor variable if the relation of T3<T4 is met.

As described above, the ultrasound diagnostic apparatus 10B changes theconditions of ultrasound transmission and reception for obtainingultrasound images to be subjected to spatial compounding based on thetemperature measurement result obtained with the temperature sensor 42.

In the illustrated embodiment, three conditions of ultrasoundtransmission and reception under which the image quality of theresulting ultrasound images is different are set in the probe 12B forthe ultrasound transmission and reception upon spatial compounding.

The first is the “transmission and reception at the normal image qualitylevel” which are those corresponding to ultrasound images ofpredetermined image quality to be combined by spatial compounding. Thesecond is the “transmission and reception at the low image qualitylevel” which are those corresponding to ultrasound images of the lowestimage quality to be combined by spatial compounding. The third is the“transmission and reception at the medium image quality level” which arethose corresponding to ultrasound images having image quality betweenthat in the transmission and reception at the normal image quality leveland that in the transmission and reception at the low image qualitylevel.

In the illustrated embodiment, the image quality is adjusted by thenumber of available channels and/or the number of sound rays (number ofscanning lines). The number of available channels (number ofsimultaneously available channels) is the number of the transducers usedin the ultrasound transmission and reception.

More specifically, the transmission and reception at the normal imagequality level are performed by setting the number of available channelsand the number of sound rays to predetermined numbers. The transmissionand reception at the medium image quality level are performed byreducing the number of available channels and/or the number of soundrays from those in the transmission and reception at the normal imagequality level. The transmission and reception at the low image qualitylevel are performed by reducing the number of available channels and/orthe number of sound rays from those in the transmission and reception atthe medium image quality level.

In the illustrated embodiment, in the transmission and reception at thenormal image quality level, the number of sound rays and the number ofavailable channels are, for example, 256 and 64, respectively. In thetransmission and reception at the medium image quality level, the numberof sound rays and the number of available channels are, for example, 128and 48, respectively. In the transmission and reception at the low imagequality level, the number of sound rays and the number of availablechannels are, for example, 96 and 32, respectively.

In this embodiment, the transmission and reception at the normal imagequality level, the transmission and reception at the medium imagequality level and the transmission and reception at the low imagequality level use different numbers of sound rays and availablechannels, respectively, but this is not the sole case of the invention.

For example, the transmission and reception at the normal image qualitylevel, the transmission and reception at the medium image quality leveland the transmission and reception at the low image quality level may beperformed by only changing the number of sound rays or the number ofavailable channels. Each type of ultrasound transmission and receptionmay have different parameters. For example, the number of sound rays mayonly be different between the transmission and reception at the normalimage quality level and the transmission and reception at the mediumimage quality level, or the number of sound rays and the number ofavailable channels may be different between the transmission andreception at the medium image quality level and the transmission andreception at the low image quality level.

As described above, upon spatial compounding, the illustrated ultrasounddiagnostic apparatus 10B performs the three types of ultrasoundtransmission and reception for three images in mutually differentdirections of ultrasound transmission and reception as conceptuallyshown in FIGS. 2 and 7A to 7C. In the ultrasound diagnostic apparatus10B, the three types of ultrasound transmission and reception which makeup a frame unit for obtaining a composite ultrasound image arerepeatedly performed on a frame basis.

For example, as shown in FIGS. 7A to 7C, the transmission controller 32Band the reception controller 34B first perform the transmission andreception for the image A for obtaining the ultrasound image A as themain image.

Then, the transmission controller 32B and the reception controller 34Bperform the transmission and reception for the image B for obtaining theultrasound image B in the direction inclined by the angle of θ withrespect to the direction for the ultrasound image A.

Then, the transmission controller 32B and the reception controller 34Bperform the transmission and reception for the image C for obtaining theultrasound image C in the direction inclined by the angle of −θ withrespect to the direction for the ultrasound image A.

In FIGS. 7A to 7C, areas each having a black letter on a whitebackground correspond to the transmission and reception at the normalimage quality level. Coarsely hatched (shaded) areas correspond to thetransmission and reception at the medium image quality level. Denselyhatched areas correspond to the transmission and reception at the lowimage quality level.

When spatial compounding is performed, the transmission controller 32Band the reception controller 34B of the probe 12B in the ultrasounddiagnostic apparatus 10B control, as described below, the drive of thetransmission drive 30 and the individual signal processors 20 a based onthe temperature measurement result obtained with the temperature sensor42, respectively.

That is, when the temperature measurement result obtained with thetemperature sensor 42 is less than T3, the transmission controller 32Band the reception controller 34B control the drive of the transmissiondrive 30 and the individual signal processors 20 a, respectively, sothat the transmission and reception for the images A, B and C are allperformed in one frame at the normal image quality level as shown inFIG. 7A.

The case in which the temperature measurement result obtained with thetemperature sensor 42 is less than T3 refers to the case in which theprobe 12B (signal processor 20) has a steady temperature.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T3 but less than T4, the transmissioncontroller 32B and the reception controller 34B control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, so that, in one frame, the transmission and reception forthe image A are performed at the normal image quality level and thetransmission and reception for the images B and C are performed at themedium image quality level as shown in FIG. 7B.

In addition, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T4, the transmissioncontroller 32B and the reception controller 34B control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, so that, in each frame, the transmission and reception forthe image A are performed at the normal image quality level and thetransmission and reception for the images B and C are performed at thelow image quality level as shown in FIG. 7C.

As is clear from the above description, in cases where the temperatureof the probe 12B is increased upon spatial compounding, the ultrasounddiagnostic apparatus 10B reduces the number of sound rays and/or thenumber of available channels in the ultrasound transmission andreception for obtaining ultrasound images to be combined into acomposite ultrasound image, thereby lowering the image quality of theultrasound images. More specifically, in the ultrasound diagnosticapparatus 10B of the invention, when the temperature of the probe 12B isincreased, the number of times the heat generation areas such as theindividual signal processors 20 a are driven or the number of times thereception signals are processed in the signal processor 20 or the likeis reduced depending on the temperature.

Therefore, according to the invention, the internal temperature of theprobe 12B can be promptly reduced by stopping the heat generation areassuch as the signal processor 20 even if the temperature of the probe 12Bis increased during spatial compounding. Even if the temperature of theprobe 12B is increased, the image quality deterioration can be minimizedby promptly reducing the temperature inside the probe 12B whilesuppressing the temperature increase therein.

In the example shown in FIGS. 7B and 7C, when the temperaturemeasurement result obtained with the temperature sensor 42 is equal toor more than T3 but less than T4 or is equal to or more than T4, theultrasound transmission and reception are performed under the samecondition for the images for which the condition of ultrasoundtransmission and reception is to be changed from the transmission andreception at the normal image quality level. However, this is not thesole case of the invention.

In other words, the transmission and reception at the medium imagequality level and the transmission and reception at the low imagequality level may be performed in one frame, or the transmission andreception at the normal image quality level, the transmission andreception at the medium image quality level and the transmission andreception at the low image quality level may be performed in one frame.

An example of the ultrasound transmission and reception is conceptuallyshown in FIGS. 8A to 8C.

In this example, as in FIG. 7A, when the temperature measurement resultobtained with the temperature sensor 42 is less than T3, thetransmission and reception for the images A, B and C are all performedat the normal image quality level as shown in FIG. 8A. As in FIG. 7B,when the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T3 but less than T4, the transmissionand reception for the image A are performed at the normal image qualitylevel, whereas those for the images B and C are performed t the mediumimage quality level as shown in FIG. 8B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T4, thetransmission and reception for the image A are performed at the normalimage quality level, those for the image B at the medium image qualitylevel and those for the image C at the low image quality level as shownin FIG. 8C. Alternatively, the transmission and reception for the imageA may be performed at the normal image quality level, those for theimage B at the low image quality level and those for the image C at themedium image quality level.

Compared to the example shown in FIGS. 7A to 7C, this method reduces theeffect of preventing heat generation but is advantageous in terms of theimage quality of the composite ultrasound images.

In the above example, when the temperature in the probe 12B isincreased, the condition of ultrasound transmission and reception ischanged from the transmission and reception at the normal image qualitylevel in the transmission and reception for the image B and/or those forthe image C but this is not the sole case of the invention. That is, thetransmission and reception for the image A may be performed by changingfrom the transmission and reception at the normal image quality level tothose at the medium or low image quality level depending on thetemperature increase.

However, the ultrasound image A is the main image. In other words, thecomposite ultrasound image produced in the diagnostic apparatus body 14Bthrough spatial compounding is the image having the region of theultrasound image A (transmission and reception for the image A).Therefore, when the transmission and reception at the normal imagequality level are included in one frame, it is more advantageous toperform the transmission and reception for the image A serving as themain image at the normal image quality level because a proper compositeultrasound image can be consistently obtained.

In the above example, the transmission and reception for the image A areperformed at the normal image quality level at any temperature but thisis not the sole case of the invention. That is, the transmission andreception for the image A may be performed at the medium or low imagequality level based on the temperature measurement result obtained withthe temperature sensor 42.

An example of the ultrasound transmission and reception is conceptuallyshown in FIGS. 9A to 9C.

In this example, as in FIG. 7A, when the temperature measurement resultobtained with the temperature sensor 42 is less than T3, thetransmission and reception for the images A, B and C are all performedat the normal image quality level as shown in FIG. 9A. As in FIG. 7B,when the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T3 but less than T4, the transmissionand reception for the image A are performed at the normal image qualitylevel, whereas those for the images B and C are performed at the mediumimage quality level as shown in FIG. 9B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T4, thetransmission and reception for the image A are performed at the mediumimage quality level, whereas those for the images B and C are performedat the low image quality level as shown in FIG. 9C.

Compared to the examples shown in FIGS. 7A-7C and 8A-8C, this method isdisadvantageous terms of the image quality but enhances the effect ofpreventing heat generation.

In this example, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T3, the ultrasoundtransmission and reception for the two images are performed by changingfrom the transmission and reception at the normal image quality level toanother. However, this is not the sole case of the invention.

The condition of ultrasound transmission and reception for only oneimage or three or more images may be changed from the transmission andreception at the normal image quality level based on the temperaturemeasurement result obtained with the temperature sensor 42.

Considering the purpose that the temperature increase within the probe12B is suppressed while minimizing the image quality deterioration dueto the temperature increase, when the temperature exceeds one of thethresholds, the ultrasound transmission and reception for two or moreimages are preferably performed by changing the condition of ultrasoundtransmission and reception from the transmission and reception at thenormal image quality level depending on the temperature. In addition, inorder to suppress the temperature increase while preventing the imagequality deterioration, when the temperature exceeds one of thethresholds, the transmission and reception for all images except theimage A (main image) are preferably performed by changing the conditionof ultrasound transmission and reception from the transmission andreception at the normal image quality level depending on thetemperature.

In addition, in the above examples, since the predetermined number uponspatial compounding is three, two temperature thresholds are provided.However, this is not the sole case of the invention and in cases wherethe predetermined number is four or more, three or more thresholds maybe provided.

The number of conditions of ultrasound transmission and receptiondetermined by the temperature is not limited to three. For example, twoconditions including the transmission and reception at the normal imagequality level and the transmission and reception at the low imagequality level may be applied. Alternatively, four or more conditionsincluding a plurality of types of transmission and reception at themedium image quality level in addition to the transmission and receptionat the normal image quality level and the transmission and reception atthe low image quality level may be applied.

In the examples shown in FIGS. 7A to 9C, the order of ultrasoundtransmission and reception in one frame is the same for all the framesbut this is not the sole case of the invention and the order ofultrasound transmission and reception of the images may be differentframe by frame.

For example, as shown in FIGS. 10A to 10C, the ultrasound transmissionand reception of the first frame, the second frame, the third frame, thefourth frame and the like may be performed in the orders of “imageB→image A→image C”, “image C→image A→image B”, “image B→image A→imageC”, “image C→image A→” image B and the like, respectively.

That is, in the second embodiment of the ultrasound diagnostic apparatus10B, as in the first embodiment, the directions of ultrasoundtransmission and reception in the last ultrasound image in the earlierone of two consecutive frames (i.e., two temporally consecutivecomposite ultrasound images) and the first ultrasound image in thesubsequent frame may be the same.

This order of ultrasound transmission and reception enables theultrasound transmission and reception to be continued in the samedirections to facilitate the control of the transmission drive 30 andthe individual signal processors 20 a.

As described above, the reception signals outputted from the probe 12Bare supplied to the diagnostic apparatus body 14B by wirelesscommunication.

Similarly to the first embodiment of the diagnostic apparatus body 14Ashown in FIG. 1, the diagnostic apparatus body 14B includes an antenna50, a wireless communication unit 52, a serial/parallel converter 54, adata storage unit 56, an image generating unit 58, a display controller62, a monitor 64, a communication controller 68, an apparatus bodycontroller 70 and an operating unit 72.

As in the above embodiment, the diagnostic apparatus body 14B includes abuilt-in power supply unit (not shown), which supplies electric powerfor drive to each component.

The antenna 50, the wireless communication unit 52, the serial/parallelconverter 54, the data storage unit 56, the image generating unit 58,the display controller 62, the monitor 64, the communication controller68 and the apparatus body controller 70 are basically the same as thosein the diagnostic apparatus body 10A shown in FIG. 1.

More specifically, the wireless communication unit 52 performs wirelesscommunication with the probe 12B via the antenna 50 to transmit controlsignals to the probe 12B and receive signals sent from the probe 12B.The wireless communication unit 52 demodulates the received signals andoutputs them to the serial/parallel converter 54 as serial sample data.

The communication controller 68 controls the wireless communication unit52 so that various control signals are transmitted according to thesettings made by the apparatus body controller 70.

The serial/parallel converter 54 converts the serial sample data intoparallel sample data. The data storage unit 56 stores at least one frameof sample data converted by the serial/parallel converter 54.

The image generating unit 58 (phase adjusting and summing unit 76, imageprocessor 78 and image combining unit 80) performs reception focusing onsample data for each image read out from the data storage unit 56 togenerate image signals representing an ultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10B, the probe 12B performs, forexample, the ultrasound transmission and reception for three images,that is, the transmission and reception for the images A, B and C.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 accordingly combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10B, the probe 12B changes the conditionof ultrasound transmission and reception for obtaining ultrasound imagesto be combined based on the temperature measurement result obtained withthe temperature sensor 42.

Therefore, the ultrasound images to be combined in the image combiningunit 80 have accordingly changed image quality such as normal, medium orlow image quality.

The display controller 62 causes the monitor 64 to display theultrasound image according to the image signals generated by the imagegenerating unit 58.

Under the control of the display controller 62, the monitor 64 displaysthe ultrasound image.

The apparatus body controller 70 controls the components in thediagnostic apparatus body 14B. The apparatus body controller 70 isconnected to the operating unit 72 to perform various input operationsincluding as to whether or not spatial compounding is to be performed.

The operation of the ultrasound diagnostic apparatus 10B shown in FIG. 6is described below.

Similarly to the ultrasound diagnostic apparatus 10A, during thediagnosis, various kinds of information inputted to the operating unit72 are first sent to the probe 12B by wireless communication and thensupplied to the probe controller 38 also in the ultrasound diagnosticapparatus 10B.

Then, ultrasonic waves are transmitted from the transducers 18 inaccordance with the drive voltage supplied from the transmission drive30 of the probe 12B.

The reception signals outputted from the transducers 18 that havereceived the ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject are supplied to the corresponding individual signalprocessors 20 a to generate sample data.

In the probe 12B, when spatial compounding is performed, the temperaturemeasurement result of the signal processor 20 obtained with thetemperature sensor 42 is sent to the transmission controller 32B and thereception controller 34B.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10B, the probe 12B adjusts the imagequality of the ultrasound images to be combined based on the temperaturemeasurement result of the reception processor 20 obtained with thetemperature sensor 42. More specifically, when spatial compounding isperformed, the probe 12B selects the condition of ultrasoundtransmission and reception for obtaining ultrasound images to becombined from among the transmission and reception at the normal imagequality level, transmission and reception at the medium image qualitylevel and transmission and reception at the low image quality levelbased on the temperature measurement result of the reception processor20 such that the image quality of the composite ultrasound image islowered each time the temperature of the reception processor 20 exceedsone of the temperature thresholds.

For example, when the temperature measured with the temperature sensor42 is less than T3, the transmission controller 32B and the receptioncontroller 34B control the operations of the transmission drive 30 andthe signal processor 20 (each individual signal processor 20 a) so thatthe transmission and reception for the images A, B and C are allperformed at the normal image quality level as shown in FIG. 7A.

When the temperature measured with the temperature sensor 42 is equal toor more than T3 but less than T4, the transmission controller 32B andthe reception controller 34B control the operations of the transmissiondrive 30 and the signal processor 20 so that the transmission andreception for the image A are performed at the normal image qualitylevel and the transmission and reception for the images B and C areperformed at the medium image quality level as shown in FIG. 7B.

When the temperature measured with the temperature sensor 42 is equal toor more than T4, the transmission controller 32B and the receptioncontroller 34B control the operations of the transmission drive 30 andthe signal processor 20 so that the transmission and reception for theimage A are performed at the normal image quality level and thetransmission and reception for the images B and C are performed at thelow image quality level as shown in FIG. 7C.

The sample data generated by the individual signal processors 20 a aresent to the parallel/serial converter 24, where the sample data isconverted into serial data. The serial data is then wirelesslytransmitted from the wireless communication unit 26 (antenna 28) to thediagnostic apparatus body 14B.

The sample data received by the wireless communication unit 52 of thediagnostic apparatus body 14B is converted into parallel data in theserial/parallel converter 54 and stored in the data storage unit 56.

Further, the sample data for each image is read out from the datastorage unit 56 to generate image signals of an ultrasound image in theimage generating unit 58. The display controller 62 causes the monitor64 to display the ultrasound image based on the image signals.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 combines the ultrasound images.

More specifically, as described above, when spatial compounding isperformed, the image combining unit 80 combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image, and outputs the image signals to the displaycontroller 62.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10B, the probe 12B selects the conditionof ultrasound transmission and reception from among the transmission andreception at the normal image quality level, transmission and receptionat the medium image quality level and transmission and reception at thelow image quality level based on the temperature measurement result ofthe reception processor 20 such that the image quality of the compositeultrasound image is lowered each time the temperature of the receptionprocessor 20 exceeds one of the temperature thresholds.

Therefore, the ultrasound images to be combined in the image combiningunit 80 are also various combinations of normal image quality images,medium image quality images and low image quality images based on thetemperature measurement results.

For example, in the above-described ultrasound transmission andreception shown in FIGS. 7A to 7C, when the temperature measured withthe temperature sensor 42 in the probe 12B is less than T3, theultrasound images A, B and C all have normal image quality as obtainedby the transmission and reception at the normal image quality level.

When the temperature measured with the temperature sensor 42 in theprobe 12B is equal to or more than T3 but less than T4, the ultrasoundimage A has normal image quality as obtained by the transmission andreception at the normal image quality level, and the ultrasound images Band C have medium image quality as obtained by the transmission andreception at the medium image quality level.

When the temperature measured with the temperature sensor 42 in theprobe 12B is equal to or more than T4, the ultrasound image A has normalimage quality as obtained by the transmission and reception at thenormal image quality level, and the ultrasound images B and C have lowimage quality as obtained by the transmission and reception at the lowimage quality level.

FIG. 11 is a conceptual block diagram showing the third embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

Many components of the ultrasound diagnostic apparatus 10C shown in FIG.11 are the same as those of the ultrasound diagnostic apparatus 10Ashown in FIG. 1. Therefore, like components are denoted by the samereference numerals and the following description mainly focuses on thedifferent features.

As in the first embodiment of the ultrasound diagnostic apparatus 10A,the ultrasound diagnostic apparatus 10C shown in FIG. 11 includes anultrasound probe 12C (hereinafter referred to as “probe 12C”) and adiagnostic apparatus body 14C. As in the above embodiment, theultrasound probe 12C is connected to the diagnostic apparatus body 14Cby wireless communication.

Similarly to the probe 12A in the first embodiment, the probe 12Ctransmits ultrasonic waves to the subject, receives ultrasonic echoesgenerated by reflection of the ultrasound waves on the subject, andoutputs reception signals of an ultrasound image in accordance with thereceived ultrasonic echoes.

There is no limitation on the type of the probe 12C and various knownultrasound probes can be used.

As in the probe 12A, the probe 12C also includes a piezoelectric unit16, a signal processor 20, a parallel/serial converter 24, a wirelesscommunication unit 26, an antenna 28, a transmission drive 30, atransmission controller 32C, a reception controller 34C, a communicationcontroller 36, a probe controller 38 and a temperature sensor 42.

The probe 12C also includes a built-in battery (not shown), whichsupplies electric power for drive to each component.

The piezoelectric unit 16, the signal processor 20, the parallel/serialconverter 24, the wireless communication unit 26, the antenna 28, thetransmission drive 30, the communication controller 36, the probecontroller 38 and the temperature sensor 42 are basically the same asthose of the probe 12A.

More specifically, the piezoelectric unit 16 is a one-dimensional ortwo-dimensional array of transducers 18 transmitting and receivingultrasonic waves.

The transmission drive 30 supplies the transducers 18 with a drivevoltage so that the transducers transmit ultrasonic waves so as to formultrasonic beams.

The transducers 18 output the reception signals of the ultrasonic echoesto individual signal processors 20 a of the signal processor 20. Asdescribed above, the individual signal processors 20 a each include anAFT, process the reception signals to generate sample data and supplythe generated sample data to the parallel/serial converter 24. Theparallel/serial converter 24 converts the parallel sample data intoserial sample data.

The ultrasound diagnostic apparatus 10C also has the function of spatialcompounding in which ultrasound images obtained by the ultrasoundtransmission and reception in mutually different directions are combinedto produce a composite ultrasound image.

Similarly to the above ultrasound diagnostic apparatus 10A, theultrasound diagnostic apparatus 10C combines, for example, threeultrasound images upon spatial compounding. Therefore, the transmissioncontroller 32C and the reception controller 34C control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, such that three types of ultrasound transmission andreception are performed in mutually different directions of ultrasoundtransmission and reception.

The probe 12C has the temperature sensor 42 for measuring thetemperature of the signal processor 20. The temperature sensor 42supplies the temperature measurement result to the reception controller34C.

Upon spatial compounding, based on the temperature measurement result,the reception controller 34C adjusts the depth of the reception signalsto be processed in the signal processor 20 and changes the depth of theultrasound images to be combined by spatial compounding.

This point will be described in detail later.

The wireless communication unit 26 generates transmission signals fromthe serial sample data and transmits the serial sample data to thediagnostic apparatus body 14C via the antenna 28.

The wireless communication unit 26 receives various control signals fromthe diagnostic apparatus body 14C and outputs the received controlsignals to the communication controller 36.

The communication controller 36 controls the wireless communication unit26. The communication controller 36 outputs the various control signalsreceived by the wireless communication unit 26 to the probe controller38.

The probe controller 38 controls various components of the probe 12Caccording to various control signals transmitted from the diagnosticapparatus body 14C.

As described above, the ultrasound diagnostic apparatus 10C of theinvention has the function of producing an image (composite ultrasoundimage) through spatial compounding.

As in the ultrasound diagnostic apparatus 10A shown in FIG. 1, theultrasound diagnostic apparatus 10C also performs, for example, thethree types of ultrasound transmission and reception in mutuallydifferent directions upon spatial compounding as conceptually shown inFIG. 12 (FIG. 2). More specifically, upon spatial compounding, the probe12C performs the three types of ultrasound transmission and reception,including the “transmission and reception for the image A” as thetransmission and reception for obtaining the main image (image includingthe whole area of the composite ultrasound image formed by spatialcompounding), the “transmission and reception for the image B” in adirection inclined by an angle of θ with respect to the direction of thetransmission and reception for the image A, and the “transmission andreception for the image C” in a direction inclined by an angle of −θwith respect to the direction of the transmission and reception for theimage A.

Also in this embodiment, when spatial compounding is performed, theprobe 12C repeatedly performs the three types of ultrasound transmissionand reception which make up a frame unit (see FIGS. 14A to 14C).

When spatial compounding is performed, the transmission controller 32Cand the reception controller 34C of the probe 12C control the drive ofthe transmission drive 30 and the individual signal processors 20 a,respectively, such that the three types of ultrasound transmission andreception are repeatedly performed.

On the other hand, when spatial compounding is performed, the diagnosticapparatus body 14C (more specifically an image combining unit 80)combines the three ultrasound images including the ultrasound image A(solid line) as the main image obtained by the transmission andreception for the image A, the ultrasound image B (broken line) obtainedby the transmission and reception for the image B, and the ultrasoundimage C (chain line) obtained by the transmission and reception for theimage C to produce a composite ultrasound image covering the region ofthe ultrasound image A.

Therefore, the number (predetermined number) of ultrasound images to becombined by spatial compounding in the ultrasound diagnostic apparatus10C is three. However, the predetermined number may be two or four ormore as in the above embodiments.

In addition, various known methods can be used to transmit and receiveultrasonic waves in different directions as in the above embodiments.

As described above, the probe 12C is provided with the temperaturesensor 42 for measuring the temperature of the signal processor 20. Thetemperature measurement result obtained with the temperature sensor 42is supplied to the reception controller 34C.

The temperature thresholds including the first temperature T5 [° C.] andthe second temperature T6 [° C.] which is higher than T5 are set for theprobe 12C (reception controller 34C). In the ultrasound diagnosticapparatus 10C, T5 and T6 may be fixed or variable if the relation ofT5<T6 is met.

As described above, in the ultrasound diagnostic apparatus 10C, whenspatial compounding is performed, the depth of the reception signalprocessing in the ultrasound transmission and reception which isperformed in the individual signal processors 20 a is changed based onthe temperature measurement result obtained with the temperature sensor42.

In the illustrated example, as conceptually shown in FIG. 12, threedepths are set in the probe 12C (reception controller 34C) for the depthof the reception signal processing in the individual signal processors20 a (depth in the directions of ultrasound transmission and reception)in the ultrasound transmission and reception for obtaining ultrasoundimages to be combined by spatial compounding.

That is, ultrasound images having three different depths are set as theultrasound images to be combined by spatial compounding. In other words,three types of ultrasound images different in size in the depthdirection are set as the ultrasound images to be combined by spatialcompounding.

In the first type, the reception signal processing is performed up tothe “depth L1” (normal depth) which is the same as that of the compositeultrasound image to be produced by spatial compounding (i.e., mainimage) and the ultrasound image having a predetermined depth (apredetermined size in the depth direction) is generated.

In the second type, the reception signal processing is performed up tothe “depth L3” (small depth) which is the smallest in the images to becombined by spatial compounding and the ultrasound image having thesmallest depth (smallest size in the depth direction) is generated.

In the third type, the reception signal processing is performed up tothe “depth L2” (medium depth) which is smaller than the depth L1 butlarger than the depth L3 and the ultrasound image having the mediumdepth (medium size in the depth direction) is generated.

The depths L1, L2 and L3 in this embodiment may be the same as ordifferent from those in the fourth embodiment to be described later.

In the illustrated example, the drive of the individual signalprocessors 20 a of the signal processor 20 (more specifically the AFEsthereof) is activated or deactivated (on/off) to adjust the depth of thereception signal processing (adjust the depth of the ultrasound images).

More specifically, when the individual signal processor 20 a performsthe reception signal processing up to the depth L1, as conceptuallyshown in FIG. 13A, a transmission pulse is applied while at the sametime the drive of the individual signal processor 20 a is activated(on), and the drive of the individual signal processor 20 a isdeactivated (off) at a point time when a time period corresponding tothe depth L1 (depth corresponding to the composite ultrasound image) haspassed.

When the individual signal processor 20 a performs the reception signalprocessing up to the depth L2, as conceptually shown in FIG. 13B, atransmission pulse is applied while at the same time the drive of theindividual signal processor 20 a is activated, and the drive of theindividual signal processor 20 a is deactivated at a point in time whena time period corresponding to the depth L2 which is smaller than thedepth L1 has passed.

In addition, when the individual signal processor 20 a performs thereception signal processing up to the depth L3, as conceptually shown inFIG. 13C, a transmission pulse is applied while at the same time thedrive of the individual signal processor 20 a is activated, and thedrive of the individual signal processor 20 a is deactivated at a pointin time when a time period corresponding to the smallest depth L3 whichis smaller than the depth L2 has passed.

As described above, as conceptually shown in FIGS. 12 and 14A to 14C,when spatial compounding is performed in the illustrated ultrasounddiagnostic apparatus 10C, the three types of ultrasound transmission andreception for three images which are made in mutually differentdirections of ultrasound transmission and reception and which make up aframe unit for obtaining a composite ultrasound image are repeatedlyperformed on a frame basis.

For example, as shown in FIGS. 12 and 14A to 14C, the transmissioncontroller 32C and the reception controller 34C first perform thetransmission and reception for the image A for obtaining the ultrasoundimage A as the main image.

Then, the transmission controller 32C and the reception controller 34Cperform the transmission and reception for the image B for obtaining theultrasound image B in the direction inclined by the angle of θ withrespect to the direction for the ultrasound image A.

Then, the transmission controller 32C and the reception controller 34Cperform the transmission and reception for the image C for obtaining theultrasound image C in the direction inclined by the angle of −θ withrespect to the direction for the ultrasound image A.

In FIGS. 14A to 14C, areas each having a black letter on a whitebackground correspond to the processing of the reception signals up tothe depth L1 (normal depth); coarsely hatched (shaded) areas correspondto the processing of the reception signals up to the depth L2 (mediumdepth); and densely hatched areas correspond to the processing of thereception signals up to the depth L3 (small depth).

When the temperature measurement result obtained with the temperaturesensor 42 is less than T5 upon spatial compounding, the receptioncontroller 34C of the probe 12C in the ultrasound diagnostic apparatus10C controls the drive of the individual signal processors 20 a so that,in one frame, the reception signal processing in the transmission andreception for the images A, B and C is all performed up to the depth L1as shown in FIG. 14A.

The case in which the temperature measurement result obtained with thetemperature sensor 42 is less than T5 refers to the case in which theprobe 12C (signal processor 20) has a steady temperature.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T5 but less than T6, the receptioncontroller 34C controls the drive of the individual signal processors 20a so that, in one frame, the reception signal processing in thetransmission and reception for the image A is performed up to the depthL1 and that in the transmission and reception for the images B and C isperformed up to the depth L2 as shown in FIG. 14B.

That is, according to this processing, spatial compounding is notperformed in the region distant from the piezoelectric unit 16 (regionbeyond the depth L2) and the deeper region of the composite ultrasoundimage is only made up of the ultrasound image A.

In addition, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T6, the receptioncontroller 34C controls the drive of the individual signal processors 20a so that, in one frame, the reception signal processing in thetransmission and reception for the image A is performed up to the depthL1 and that in the transmission and reception for the images B and C isperformed up to the depth L3 as shown in FIG. 14C.

That is, according to this processing, the three ultrasound images arecombined by spatial compounding to obtain a high-quality image only inthe region near the piezoelectric unit 16.

As is clear from the above description, in cases where the temperatureof the probe 12C is increased upon spatial compounding, the ultrasounddiagnostic apparatus 10C reduces the processing depth in the processingof the reception signals from the ultrasound transmission and receptionfor obtaining ultrasound images to be combined into a compositeultrasound image. That is, when the temperature of the probe 12C isincreased, the ultrasound diagnostic apparatus 10C reduces the drivetime of the individual signal processors 20 a for processing thereception signals from the ultrasonic echoes depending on thetemperature.

Therefore, according to the invention, the internal temperature of theprobe 12C can be promptly reduced by stopping the signal processor 20which is the major heat generation area even if the temperature of theprobe 12C is increased during spatial compounding. Even if thetemperature of the probe 12C is increased, the image qualitydeterioration can be minimized by promptly reducing the temperatureinside the probe 12C while suppressing the temperature increase therein.

In the example shown in FIGS. 14A to 14C, the processing depth of allthe reception signals is the same in one frame making up a compositeultrasound image. However, this is not the sole case of the inventionand the reception signals of one or more ultrasound images in each frame(each composite ultrasound image) may be different.

An example of the reception signal processing is conceptually shown inFIGS. 15A to 15C.

In this example, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T6, as shown in FIG.15C, the reception signal processing in the transmission and receptionfor the image A is performed up to the depth L1 for all the frames butthe reception signal processing for the other images is performed sothat the depth is different between the odd frames and the even frames.More specifically, the reception signal processing for the images B andC is performed up to the depth T3 in the odd frames and up to the depthL2 in the even frames.

FIG. 15A showing the case where the temperature measurement result isless than T5 and FIG. 15B showing the case where the temperaturemeasurement result is equal to or more than T5 but less than T6 aresimilar to FIG. 14A and FIG. 14B, respectively.

Therefore, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T6, theultrasound images A to C as shown in FIG. 15D are combined to obtain thecomposite ultrasound image in each odd frame, whereas the ultrasoundimages A to C as shown in FIG. 15E are combined to obtain the compositeultrasound image in each even frame.

In this example, the depth of the images to be combined by spatialcompounding can be increased in every two frames and therefore the imagequality deterioration in the section from the deeper end of the depth L3to the deeper end of the depth L2 can be reduced compared to the exampleshown in FIGS. 14A to 14C in which the images produced by spatialcompounding are observed as consecutive images.

In the example shown in FIGS. 14A to 14C, when the temperature in thecase shown in FIG. 14B is equal to or more than T5 but less than T6, thesame ultrasound image as that shown in FIG. 15E is obtained, and whenthe temperature in the case shown in FIG. 14C is equal to or more thanT6, the same ultrasound image as that shown in FIG. 15D is obtained.

In the above example, when the temperature measurement result obtainedwith the temperature sensor 42 is equal to or more than T5 but less thanT6 or equal to or more than T6, the images in one frame for which thedepth of the reception signal processing was changed from the depth L1both have the same depth. However, this is not the sole case of theinvention.

In other words, the reception signal processing up to the depth L2 andthat up to the depth L3 may be performed in one frame. The receptionsignal processing up to the depth L1, that up to the depth L2 and thatup to the depth L3 may be performed in one frame.

An example of the reception signal processing is conceptually shown inFIGS. 16A to 16C.

In this example, as in FIG. 14A, when the temperature measurement resultobtained with the temperature sensor 42 is less than T5, the receptionsignal processing for all the images A, B and C is performed up to thedepth L1 as shown in FIG. 16A. As in FIG. 14B, when the temperaturemeasurement result obtained with the temperature sensor 42 is equal toor more than T5 but less than T6, the reception signal processing forthe image A is performed up to the depth L1 and that for the images Band C is performed up to the depth L2 as shown in FIG. 16B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T6, thereception signal processing for the image A is performed up to the depthL1, that for the image B up to the depth L2 and that for the image C upto the depth L3 as shown in FIG. 16C. Alternatively, the depth of theimages A, B and C may be set to the depth L1, depth L3 and the depth L2,respectively.

Compared to the example shown in FIGS. 14A to 14C, this method reducesthe effect of preventing heat generation but is advantageous in terms ofthe image quality of the composite ultrasound images.

In this example, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T6, the receptionsignal processing up to the depth L2 and the reception signal processingup to the depth L3 may be alternately performed for the images B and C.

An example is shown in FIGS. 17A to 17E.

In the example shown in FIGS. 17A to 17E, when the temperaturemeasurement result obtained with the temperature sensor 42 is equal toor more than T6, in the odd frames; the reception signal processing forthe image A is performed up to the depth L1, that for the image B up tothe depth L2 and that for the image C up to the depth L3 as shown inFIG. 17C (as in FIG. 16C). In contrast, in the even frames, thereception signal processing for the image A is performed up to the depthL1 but that for the images B and C is performed up to the depths L3 andL2, respectively.

Also in FIGS. 17A and 17B, FIG. 17A showing the case where thetemperature measurement result is less than T5 and FIG. 17B showing thecase where the temperature measurement result is equal to or more thanT5 but less than T6 are similar to FIG. 16A and FIG. 16B, respectively.

Therefore, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T6, theultrasound images A to C having three different depths as shown in FIG.17D are combined to obtain the composite ultrasound image in each oddframe, whereas the ultrasound images A to C having three differentdepths as shown in FIG. 17E are combined to obtain the compositeultrasound image in each even frame.

In this example, the composite ultrasound image shown in FIG. 17D andthe composite ultrasound image shown in FIG. 17E are replaced by eachother in every two frames. Therefore, in the regions shown by theoblique lines in FIGS. 17D and 17E which are made up of one image,one-image composition and two-image composition are alternately used invery two frames. Accordingly, when the images produced by spatialcompounding are observed as continuous images, portions havingcontinuously and partly deteriorating image quality can be eliminated tosuppress the deterioration of the mage quality of the compositeultrasound images.

In the above example, when the temperature in the probe 12C isincreased, the depth of the reception signal processing is changed to L2or L3 in the transmission and reception for the image B and/or those forthe image C but this is not the sole case of the invention. That is, thedepth of the reception signal processing in the transmission andreception for the image A may be changed to L2 or L3 depending on thetemperature increase.

However, the ultrasound image A is the main image. In other words, thecomposite ultrasound image produced in the diagnostic apparatus body 14Cthrough spatial compounding is the image having the region of theultrasound image A (transmission and reception for the image A).Therefore, when the reception signal processing up to the depth L1 isincluded in one frame, it is more advantageous to process the receptionsignals derived from the transmission and reception for the image Aserving as the main image up to the depth L1 because a proper compositeultrasound image can be consistently obtained.

In the above example, the processing for at least one image (thereception signal processing for the image A) is performed up to thedepth L1 at any temperature. However, this is not the sole case of theinvention and the reception signal processing for all the images may beperformed up to the depth L2 or L3 depending on the temperature.

An example of the ultrasound transmission and reception is conceptuallyshown in FIGS. 18A to 18C.

In this example, as in FIG. 14A, when the temperature measurement resultobtained with the temperature sensor 42 is less than T5, the receptionsignal processing for the images A, B and C is all performed up to thedepth L1 as shown in FIG. 18A. As in FIG. 14B, when the temperaturemeasurement result obtained with the temperature sensor 42 is equal toor more than T5 but less than the reception signal processing for theimage A is performed up to the depth L1 and that for the images B and Cis performed up to the depth L2 as shown in FIG. 18B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T6, thereception signal processing for the image A is performed up to the depthL2, and that for the images B and C up to the depth L3 as shown in FIG.18C.

According to this example, the depth of the resulting compositeultrasound image is reduced but the effect of preventing heat generationis increased.

In this example, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T5, the depth of thereception signal processing for the two images was changed from thedepth L1 but this is not the sole case of the invention. That is, thedepth of the reception signal processing for only one image or three ormore images may be changed from the depth L1 based on the temperaturemeasurement result obtained with the temperature sensor 42.

Considering the purpose that the temperature increase within the probe12C is suppressed while minimizing the image quality deterioration dueto the temperature increase, when the temperature exceeds one of thethresholds, the depth of the reception signal processing for two or moreimages is preferably changed from the depth L1. In addition, in order tosuppress the temperature increase while preventing the image qualitydeterioration, when the temperature exceeds one of the thresholds, thedepth of the reception signal processing for all the images except theimage A (main image) is preferably changed from the depth L1 dependingon the temperature.

In addition, in the above examples, since the predetermined number uponspatial compounding is three, two temperature thresholds are provided.However, this is not the sole case of the invention and in cases wherethe predetermined number is four or more, three or more thresholds maybe provided.

The number of depths set for the reception signal processing dependingon the temperature is also not limited to three. For example, two depthsincluding the normal depth (L1) and the small depth (L3) may beprovided. Alternatively, four or more depths of reception signalprocessing may be provided by setting a plurality of medium depths suchas the depth L2-1 and the depth L2-2 between the normal depth L1 and thesmall depth L3.

In the examples shown in FIGS. 14A to 18C, the order of ultrasoundtransmission and reception in one frame is the same for all the frames.However, this is not the sole case of the invention and the order ofultrasound transmission and reception of the images in each frame may bedifferent.

For example, as shown in FIGS. 19A to 19C, the ultrasound transmissionand reception of the first frame, the second frame, the third frame, thefourth frame and the like may be performed in the orders of “imageB→image A→image C”, “image C→image A→image B”, “image B→image A→imageC”, “image C→image A→mage B” and the like, respectively.

That is, also in the third embodiment of the ultrasound diagnosticapparatus 10C, as in the first embodiment, the directions of ultrasoundtransmission and reception in the last ultrasound image in the earlierone of two consecutive frames (i.e., two temporally consecutivecomposite ultrasound images) and the first ultrasound image in thesubsequent frame may be the same.

This order of ultrasound transmission and reception enables theultrasound transmission and reception to be continued in the samedirections to facilitate the control of the transmission drive 30 andthe individual signal processors 20 a.

As described above, the reception signals outputted from the probe 12Care supplied to the diagnostic apparatus body 14C by wirelesscommunication.

Similarly to the first embodiment of the diagnostic apparatus body 10Ashown in FIG. 1, the diagnostic apparatus body 14C includes an antenna50, a wireless communication unit 52, a serial/parallel converter 54, adata storage unit 56, an image generating unit 58, a display controller62, a monitor 64, a communication controller 68, an apparatus bodycontroller 70 and an operating unit 72.

As in the above embodiment, the diagnostic apparatus body 14C includes abuilt-in power supply unit (not shown), which supplies electric powerfor drive to each component.

The antenna 50, the wireless communication unit 52, the serial/parallelconverter 54, the data storage unit 56, the image generating unit 58,the display controller 62, the monitor 64, the communication controller68 and the apparatus-body controller 70 are basically the same as thosein the diagnostic apparatus body 10A shown in FIG. 1.

More specifically, the wireless communication unit 52 performs wirelesscommunication with the probe 12C via the antenna 50 to transmit controlsignals to the probe 12C and receive signals sent from the probe 12C.The wireless communication unit 52 demodulates the received signals andoutputs them to the serial/parallel converter 54 as serial sample data.

The communication controller 68 controls the wireless communication unit52 so that various control signals are transmitted according to thesettings made by the apparatus body controller 70.

The serial/parallel converter 54 converts the serial sample data intoparallel sample data. The data storage unit 56 stores at least one frameof sample data converted by the serial/parallel converter 54.

The image generating unit 58 (phase adjusting and summing unit 76, imageprocessor 78 and image combining unit 80) performs reception focusing onsample data for each image read out from the data storage unit 56 togenerate image signals representing an ultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10C, the probe 12C performs, forexample, the ultrasound transmission and reception for three images,that is, the transmission and reception for the images A, B and C.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 accordingly combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10C, the probe 12C changes, based on thetemperature measurement result obtained with the temperature sensor 42,the depth of the ultrasonic echoes to be subjected to the receptionsignal processing which is used to obtain the ultrasound images to becombined. Therefore, the ultrasound images to be combined by spatialcompounding accordingly have a depth (size in the depth direction)corresponding to the depth L1, L2 or L3.

The display controller 62 causes the monitor 64 to display theultrasound image according to the image signals generated by the imagegenerating unit 58.

Under the control of the display controller 62, the monitor 64 displaysthe ultrasound image.

The apparatus body controller 70 controls the components in thediagnostic apparatus body 14C. The apparatus body controller 70 isconnected to the operating unit 72 to perform various input operationsincluding as to whether or not spatial compounding is to be performed.

The operation of the ultrasound diagnostic apparatus 10C shown in FIG.11 is described below.

Similarly to the ultrasound diagnostic apparatus 10A, during thediagnosis, various kinds of information inputted to the operating unit72 are first sent to the probe 12C by wireless communication and thensupplied to the probe controller 38 also in the ultrasound diagnosticapparatus 10C.

Then, ultrasonic waves are transmitted from the transducers 18 inaccordance with the drive voltage supplied from the transmission drive30 of the probe 12C.

The reception signals outputted from the transducers 18 that havereceived the ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject are supplied to the corresponding individual signalprocessors 20 a to generate sample data.

In the probe 12C, when spatial compounding is performed, the temperaturemeasurement result of the signal processor 20 obtained with thetemperature sensor 42 is sent to the reception controller 34C.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10C, the probe 12C adjusts, based on thetemperature measurement result of the reception processor 20 obtainedwith the temperature sensor 42, the depth in the reception signalprocessing for obtaining the ultrasound images to be combined. Morespecifically, the probe 12C sets the depth of the reception signalprocessing for the ultrasound images to be combined to one of the depthsL1, L2 and L3 so that the depth of any of the ultrasound images to becombined may be reduced each time the temperature exceeds one of thethresholds according to the temperature measurement result obtained withthe temperature sensor 42 and controls the drive of the individualsignal processors 20 a for processing the reception signals.

For example, when the temperature measured with the temperature sensor42 is less than T5, the reception controller 34C controls the operationof the signal processor 20 (individual signal processors 20 a) so as toprocess the reception signals for all of the images A, B and C up to thedepth L1 as shown in 14A.

When the temperature measured with the temperature sensor 42 is equal toor more than T5 but less than T6, the reception controller 34C controlsthe operation of the signal processor 20 so as to process the receptionsignals for the image A up to the depth L1 and those for the images Band C up to the depth L2 as shown in 14B.

In addition, when the temperature measured with the temperature sensor42 is equal to or more than T6, the reception controller 34C controlsthe operation of the signal processor 20 so as to process the receptionsignals for the image A up to the depth L1 and those for the images Band C up to the depth L3 as shown in 14C.

The sample data generated by the individual signal processors 20 a aresent to the parallel/serial converter 24, where the sample data isconverted into serial data. The serial data is then wirelesslytransmitted from the wireless communication unit 26 (antenna 28) to thediagnostic apparatus body 14C.

The sample data received by the wireless communication unit 52 of thediagnostic apparatus body 14C is converted into parallel data in theserial/parallel converter 54 and stored in the data storage unit 56.

Further, the sample data for each image is read out from the datastorage unit 56 to generate image signals of an ultrasound image in theimage generating unit 58. The display controller 62 causes the monitor64 to display the ultrasound image based on the image signals.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 combines the ultrasound images.

More specifically, as described above, when spatial compounding isperformed, the image combining unit 80 combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image, and outputs the image signals to the displaycontroller 62.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10C, the probe 12C controls the drive ofthe individual signal processors 20 a based on the temperaturemeasurement result obtained with the temperature sensor 42 such that thedepth of any of the ultrasound images to be combined is reduced eachtime the temperature exceeds one of the temperature thresholds.Therefore, the ultrasound images to be combined in the image combiningunit 80 are also various combinations of normal depth images, mediumdepth images and small depth images based on the temperature measurementresults obtained with the temperature sensor 42.

For example, in the above example shown in FIGS. 14A to 14C, when thetemperature measured with the temperature sensor 42 in the probe 12C isless than T5, the ultrasound images A, B and C to be combined in theimage combining unit 80 all have the normal depth. When the temperaturemeasured with the temperature sensor 42 in the probe 12C is equal to ormore than T5 but less than T6, the ultrasound images to be combined inthe image combining unit 80 include the ultrasound image A having thenormal depth and the ultrasound images B and C having the medium depth.In addition, when the temperature measured with the temperature sensor42 in the probe 12C is equal to or more than T6, the ultrasound imagesto be combined in the image combining unit 80 include the ultrasoundimage A having the normal depth and the ultrasound images B and C havingthe small depth.

FIG. 20 is a conceptual block diagram showing the fourth embodiment ofthe ultrasound diagnostic apparatus according to the first aspect of theinvention.

Many components of the ultrasound diagnostic apparatus 10D shown in FIG.20 are the same as those of the ultrasound diagnostic apparatus 10Ashown in FIG. 1. Therefore, like components are denoted by the samereference numerals and the following description mainly focuses on thedifferent features.

As in the first embodiment of the ultrasound diagnostic apparatus 10A,the ultrasound diagnostic apparatus 10D shown in FIG. 20 includes anultrasound probe 12D (hereinafter referred to as “probe 12D”) and adiagnostic apparatus body 14D. As in the above embodiment, theultrasound probe 12D is connected to the diagnostic apparatus body 14Dby wireless communication.

Similarly to the probe 12A in the first embodiment, the probe 12Dtransmits ultrasonic waves to the subject, receives ultrasonic echoesgenerated by reflection of the ultrasound waves on the subject, andoutputs reception signals of an ultrasound image in accordance with thereceived ultrasonic echoes.

There is no limitation on the type of the probe 12D and various knownultrasound probes can be used.

As in the probe 12A, the probe 12D also includes a piezoelectric unit16, a signal processor 20, a parallel/serial converter 24, a wirelesscommunication unit 26, an antenna 28, a transmission drive 30, atransmission controller 32D, a reception controller 34D, a communicationcontroller 36, a probe controller 38 and a temperature sensor 42.

The probe 12D also includes a built-in battery (not shown), whichsupplies electric power for drive to each component.

The piezoelectric unit 16, the signal processor 20, the parallel/serialconverter 24, the wireless communication unit 26, the antenna 28, thetransmission drive 30, the communication controller 36, the probecontroller 38 and the temperature sensor 42 are basically the same asthose of the probe 12A.

More specifically, the piezoelectric unit 16 is a one-dimensional ortwo-dimensional array of transducers 18 transmitting and receivingultrasonic waves.

The transmission drive 30 supplies the transducers 18 with a drivevoltage so that the transducers transmit ultrasonic waves so as to formultrasonic beams.

The transducers 18 output the reception signals of the ultrasonic echoesto individual signal processors 20 a of the signal processor 20. Asdescribed above, each individual signal processor 20 a has an AFE,processes the reception signals to generate sample data and supplies thegenerated sample data to the parallel/serial converter 24. Theparallel/serial converter 24 converts the parallel sample data intoserial sample data.

The ultrasound diagnostic apparatus 10D also has the function of spatialcompounding in which ultrasound images obtained by the ultrasoundtransmission and reception in mutually different directions are combinedto produce a composite ultrasound image.

Similarly to the above ultrasound diagnostic apparatus 10A, theultrasound diagnostic apparatus 10D combines, for example, threeultrasound images upon spatial compounding. Therefore, the transmissioncontroller 32D and the reception controller 34D control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, such that three types of ultrasound transmission andreception are performed in mutually different directions of ultrasoundtransmission and reception.

The probe 12D has the temperature sensor 42 for measuring thetemperature of the signal processor 20. The temperature sensor 42supplies the temperature measurement result to the reception controller34D.

Upon spatial compounding, based on the temperature measurement result,the reception controller 34D adjusts the depth of the reception signalsto be processed in the signal processor 20 and reduces the number ofsound rays in the regions of the ultrasound images to be combined byspatial compounding beyond the predetermined depth.

This point will be described in detail later.

The wireless communication unit 26 generates transmission signals fromthe serial sample data and transmits the serial sample data to thediagnostic apparatus body 14D via the antenna 28.

The wireless communication unit 26 receives various control signals fromthe diagnostic apparatus body 14D and outputs the received controlsignals to the communication controller 36.

The communication controller 36 controls the wireless communication unit26. The communication controller 36 outputs the various control signalsreceived by the wireless communication unit 26 to the probe controller38.

The probe controller 38 controls various components of the probe 12Daccording to various control signals transmitted from the diagnosticapparatus body 14D.

As described above, the ultrasound diagnostic apparatus 10D of theinvention has the function of producing an image (composite ultrasoundimage) through spatial compounding.

As in the ultrasound diagnostic apparatus 10A shown in FIG. 1, theultrasound diagnostic apparatus 10D also performs, for example, thethree types of ultrasound transmission and reception in mutuallydifferent directions upon spatial compounding as conceptually shown inFIG. 21A (FIG. 2). More specifically, upon spatial compounding, theprobe 12D performs the three types of ultrasound transmission andreception, including the “transmission and reception for the image A” asthe ultrasound transmission and reception for obtaining the main image(image including the whole area of the composite ultrasound image formedby spatial compounding), the “transmission and reception for the imageB” in a direction inclined by an angle of θ with respect to thedirection of the transmission and reception for the image A, and the“transmission and reception for the image C” in a direction inclined byan angle of −θ with respect to the direction of the transmission andreception for the image A.

Also in this embodiment, when spatial compounding is performed, theprobe 12D repeatedly performs the three types of ultrasound transmissionand reception which make up a frame unit (see FIGS. 23A to 23C).

When spatial compounding is performed, the transmission controller 32Dand the reception controller 34D of the probe 12D control the drive ofthe transmission drive 30 and the individual signal processors 20 a,respectively, such that the three types of ultrasound transmission andreception are repeatedly performed.

On the other hand, when spatial compounding is performed, the diagnosticapparatus body 14D (more specifically an image combining unit 80)combines the three ultrasound images including the ultrasound image A(solid line) as the main image obtained by the transmission andreception for the image A, the ultrasound image B (broken line) obtainedby the transmission and reception for the image B, and the ultrasoundimage C (chain line) obtained by the transmission and reception for theimage C to produce a composite ultrasound image covering the region ofthe ultrasound image A.

Therefore, the number (predetermined number) of ultrasound images to becombined by spatial compounding in the ultrasound diagnostic apparatus10D is three. However, the predetermined number may be two or four ormore as in the above embodiments.

In addition, various known methods can be used to transmit and receiveultrasonic waves in different directions as in the above embodiments.

As described above, the probe 12D is provided with the temperaturesensor 42 for measuring the temperature of the signal processor 20. Thetemperature measurement result obtained with the temperature sensor 42is supplied to the reception controller 34D.

The temperature thresholds including the first temperature T7 [° C.] andthe second temperature T8 [° C.] which is higher than T7 are set for theprobe 12D (the reception controller 34D). In the ultrasound diagnosticapparatus 10D, T7 and T8 may be fixed or variable if the relation ofT7<T8 is met.

In the ultrasound diagnostic apparatus 10D, when spatial compounding isperformed, the number of sound rays in the ultrasound image is reducedin the region beyond the predetermined depth based on the temperaturemeasurement result obtained with the temperature sensor 42.

In the illustrated example, as conceptually shown in FIG. 21A, threedepths are set in the probe 12D (reception controller 34D) for the depth(depth in the directions of ultrasound transmission and reception)beyond which the number of sound rays is reduced upon spatialcompounding. The first is the depth L1 (normal depth) within which thenumber of sound rays is not reduced, that is, all the sound rays havethe same depth as that of the composite ultrasound image to be producedby spatial compounding. The second is the shallowest or smallest depthL3. The third is the depth L2 (medium depth) which is the depth betweenthe depth L1 and the depth L3.

For example, the probe 12D reduces the number of sound rays byeliminating one of every two sound rays based on the temperaturemeasurement result obtained with the temperature sensor 42.

When the number of sound rays is reduced beyond the depth L2, the soundrays for producing the ultrasound image is as conceptually shown in FIG.21B (illustrated by the ultrasound image B) in which the sound rays areshown by thin solid lines and the eliminated sound rays are shown bythin broken lines. When the number of sound rays is reduced beyond thedepth L3, the sound rays for producing the ultrasound image is asconceptually shown in FIG. 21C.

The portions of the image corresponding to the sound rays eliminated bythe probe 12D, that is, the portions shown by thin broken lines areproduced later by interpolation using the surrounding sound, rays in theimage generating unit 58 of the diagnostic apparatus body 14D.

In this embodiment, the number of sound rays is reduced in the regionbeyond the predetermined depth by eliminating one of every two soundrays as in the illustrated case (the number of sound rays is reduced byhalf). However, this is not the sole case of the invention. Therefore,in this embodiment, the number of sound rays may be reduced in theregion beyond the predetermined depth by eliminating one of every threesound rays (the number of sound rays is reduced to two-thirds) or byeliminating one of every four sound rays (the number of sound rays isreduced to three-fourths).

Alternatively, the number of sound rays in the region beyond thepredetermined depth may be reduced by eliminating two or more than twoconsecutive sound rays.

In the illustrated example, the drive of the individual signalprocessors 20 a of the signal processor 20 (more specifically the AFEsthereof) is activated or deactivated (on/off) to reduce the number ofsound rays in the region beyond the predetermined depth.

In the case of the depth L1, that is, when the number of sound rays isnot reduced, as conceptually shown in FIG. 22A, for all the sound rays,a transmission pulse is applied while at the same time the drive of theindividual signal processors 20 a is activated (on), and the drive ofthe individual signal processors 20 a is deactivated (off) when a timeperiod corresponding to the depth L1 (depth corresponding to thecomposite ultrasound image) has passed.

When the number of sound rays is reduced beyond the depth L2, asconceptually shown in FIG. 22B, a transmission pulse is applied while atthe same time the drive of the individual signal processors 20 a isactivated, and the drive of the individual signal processors 20 a isdeactivated in the corresponding sound rays (sound rays to be eliminatedbeyond the predetermined depth) at a point in time when a time periodcorresponding to the depth L2 which is smaller than the depth L1 haspassed.

That is, in the example in which one of every two sound rays iseliminated, the individual signal processors 20 a alternately performthe drive shown in FIG. 22A and the drive shown in FIG. 22B on the basisof every two sound rays.

When the number of sound rays is reduced beyond the depth L3, asconceptually shown in FIG. 22C, a transmission pulse is applied while atthe same time the drive of the individual signal processors 20 a isactivated, and the drive of the individual signal processors 20 a isdeactivated in the corresponding sound rays at a point in time when atime period corresponding to the smallest depth L3 which is smaller thanthe depth L2 has passed.

That is, in the example in which one of every two sound rays iseliminated, the individual signal processors 20 a alternately performthe drive shown in FIG. 22A and the drive shown in FIG. 22C on the basisof every two sound rays.

As described above, when spatial compounding is performed in theillustrated ultrasound diagnostic apparatus 10D, as conceptually shownin FIGS. 21A and 23A to 23C, the three types of ultrasound transmissionand reception for three images which are made in mutually differentdirections of ultrasound transmission and reception and which make up aframe unit for obtaining a composite ultrasound image are repeatedlyperformed on a frame basis.

For example, the transmission controller 32D and the receptioncontroller 34D first perform the transmission and reception for theimage A for obtaining the ultrasound image A as the main image as shownin FIGS. 21A and 23A to 23C.

Then, the transmission controller 32D and the reception controller 34Dperform the transmission and reception for the image B for obtaining theultrasound image B in the direction inclined by the angle of θ withrespect to the direction for the ultrasound image A.

Then, the transmission controller 32D and the reception controller 34Dperform the transmission and reception for the image C for obtaining theultrasound image C in the direction inclined by the angle of −θ withrespect to the direction for the ultrasound image A.

In FIGS. 23A to 23C, areas each having a black letter on a whitebackground correspond to the ultrasound transmission and reception up tothe depth L1 (normal depth), that is, the ultrasound transmission andreception for the image in which the number of sound rays is notreduced; coarsely hatched (shaded) areas correspond to the ultrasoundtransmission and reception for the image in which the number of soundrays is reduced beyond the depth L2 (medium depth); and densely hatchedareas correspond to the ultrasound transmission and reception for theimage in which the number of sound rays is reduced beyond the depth L3(small depth).

When the temperature measurement result obtained with the temperaturesensor 42 is less than T7 upon spatial compounding, the receptioncontroller 34D of the probe 12D in the ultrasound diagnostic apparatus10D controls the drive of the individual signal processors 20 a so thatthe number of sound rays is not reduced in the transmission andreception for all the images A, B and C in one frame (the receptionsignal processing is performed up to the depth L1) as shown in FIG. 23A.

The case in which the temperature measurement result obtained with thetemperature sensor 42 is less than T7 refers to the case in which theprobe 12D (signal processor 20) has a steady temperature.

When the temperature measurement result obtained with the temperaturesensor 42 is equal to or more than T7 but less than T8, the receptioncontroller 34D controls the drive of the individual signal processors 20a so that, in one frame, the number of sound rays is not reduced in thetransmission and reception for the image A but is reduced in thetransmission and reception for the images B and C beyond the depth L2 asshown in FIG. 23B.

That is, this processing reduces the image quality of the image formedby spatial compounding in the region distant from the piezoelectric unit16 (region beyond the depth L2).

In addition, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T8, the receptioncontroller 34D controls the drive of the individual signal processors 20a, so that, in one frame, the number of sound rays is not reduced in thetransmission and reception for the image A but is reduced in thetransmission and reception for the images B and C beyond the depth L3 asshown in FIG. 23C.

That is, this processing reduces the image quality of the image formedby spatial compounding in the region distant from the vicinity of thepiezoelectric unit 16 (region beyond the depth L3).

As is clear from the above description, in cases where the temperatureof the probe 12D is increased upon spatial compounding, the ultrasounddiagnostic apparatus 10D of the invention reduces the number of soundrays in the regions of the ultrasound images beyond the predetermineddepth by processing the reception signals in the ultrasound transmissionand reception for obtaining the ultrasound images to be combined into acomposite ultrasound image. That is, when the temperature of the probe12D is increased, the ultrasound diagnostic apparatus 10D of theinvention reduces the drive time of the individual signal processors 20a for processing the reception signals from the ultrasonic echoesdepending on the temperature.

Therefore, according to the invention, the internal temperature of theprobe 12D can be promptly reduced by stopping the signal processor 20which is the major heat generation area even if the temperature of theprobe 12D is increased during spatial compounding. Even if thetemperature of the probe 12D is increased, the image qualitydeterioration can be minimized by promptly reducing the temperatureinside the probe 12D while suppressing the temperature increase therein.

In the example shown in FIGS. 23A to 23C, the processing depth of allthe reception signals is the same in one frame making up the compositeultrasound image. However, this is not the sole case of the inventionand the reception signal processing depth of one or more ultrasoundimages each frame (each composite ultrasound image) may be different.

For example, in the example shown in FIGS. 23A to 23C, the number ofsound rays is reduced in all the frames beyond the depth L3 in thetransmission and reception for the images B and C when the temperaturemeasurement result obtained with the temperature sensor 42 is equal toor more than T8. However, this is not the sole case of the invention.

For example, as in the above case, when the temperature measurementresult obtained with the temperature sensor 42 is less than T7, thenumber of sound rays is not reduced in the ultrasound transmission andreception for all the images as shown in FIG. 24A, and when thetemperature measurement result obtained with the temperature sensor 42is equal to or more than T7 but less than T8, the number of sound raysis not reduced in the transmission and reception for the image A but isreduced in the transmission and reception for the images B and C beyondthe depth L2 as shown in FIG. 24B.

In contrast, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T8, for example, theprocess may be applied in which the number of sound rays is likewise notreduced in the transmission and reception for the image A in all theframes but is reduced in each odd frame in the transmission andreception for the images B and C beyond the depth L3 and in each evenframe in the transmission and reception for the images B and C beyondthe depth L2 as shown in FIG. 24C.

In this example, one of every two frames can have an increased depthbeyond which no sound ray is provided. Therefore, when the imagesproduced by spatial compounding are observed as continuous images, theimage quality deterioration in the section from the deeper end of thedepth L3 to the deeper end of the depth L2 can be reduced compared tothe example shown in FIGS. 23A to 23C.

In the above example, when the temperature measurement result obtainedwith the temperature sensor 42 is equal to or more than T7 but less thanT8 or equal to or more than T8, the images in one frame in which thenumber of sound rays is reduced have no sound ray beyond the same depth.However, this is not the sole case of the invention.

In other words, reduction in the number of sound rays beyond the depthL2 and reduction in the number of sound rays beyond the depth L3 maycoexist in one frame. Alternatively, non-reduction in the number ofsound rays, reduction in the number of sound rays beyond the depth L2and reduction in the number of sound rays beyond the depth L3 maycoexist in one frame.

An example of the reception signal processing is conceptually shown inFIGS. 25A to 25C.

In this example, as in the above example, when the temperaturemeasurement result obtained with the temperature sensor 42 is less thanT7, the number of sound rays is not reduced in the transmission andreception for all the images A, B and C as shown in FIG. 25A. As in theabove example, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T7 but less than T8, thenumber of sound rays is not reduced in the transmission and receptionfor the image A but is reduced in the transmission and reception for theimages B and C beyond the depth L2 as shown in FIG. 25B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T8, thenumber of sound rays is not reduced in the transmission and receptionfor the image A but is reduced in the transmission and reception for theimages B and C beyond the depths L2 and 13, respectively, as shown inFIG. 25C. Alternatively, the depth of the images A, B and C may be setto L1, L3 and L2, respectively.

Compared to the example shown in FIGS. 23A to 23C, this example reducesthe effect of preventing heat generation but is advantageous in terms ofthe image quality of the composite ultrasound images.

In this example, when the temperature measurement result obtained withthe temperature sensor 42 is equal to or more than T8, reduction in thenumber of sound rays beyond the depth L2 and reduction in the number ofsound rays beyond the depth L3 may be alternately performed for theimages B and C.

For example, as in the above example, when the temperature measurementresult obtained with the temperature sensor 42 is less than T7, thenumber of sound rays is not reduced in the ultrasound transmission andreception for all the images as shown in FIG. 26A, and when thetemperature measurement result is equal to or more than T7 but less thanT8, the number of sound rays is not reduced in the transmission andreception for the image A but is reduced in the transmission andreception for the images B and C beyond the depth L2 as shown in FIG.26B.

In contrast, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T8, for example, theprocess may be applied in which the number of sound rays is likewise notreduced in the transmission and reception for the image A in all theframes but is reduced in each odd frame in the transmission andreception for the images B and C beyond the depths L2 and L3,respectively, and in each even frame in the transmission and receptionfor the images B and C beyond the depths L3 and L2, respectively, asshown in FIG. 26C.

In this example, the region beyond the depth L3 where the number ofsound rays is reduced is repeated in the ultrasound images to becombined by spatial compounding on the basis of every two frames.Therefore, any region where the image quality is continuouslydeteriorated can be eliminated from the composite ultrasound images tosuppress the image quality, deterioration when the images produced byspatial compounding are observed as continuous images.

In the above example, when the temperature in the probe 12D isincreased, the transmission and reception for the image B and/or thosefor the image C are performed by reducing the number of sound rays inthe region beyond the predetermined depth but this is not the sole caseof the invention. That is, the transmission and reception for the imageA may be performed by reducing the number of sound rays in the regionbeyond the predetermined depth depending on the temperature increase.

However, the ultrasound image A is the main image. In other words, thecomposite ultrasound image produced in the diagnostic apparatus body 14Dthrough spatial compounding is the image having the region of theultrasound image A (derived from the transmission and reception for theimage A). Therefore, when the ultrasound transmission and receptionwhich does not involve the reduction in the number of sound rays isincluded in one frame, it is more advantageous to perform thetransmission and reception for the image A serving as the main imagewithout reducing the number of sound rays because a proper compositeultrasound image can be consistently obtained.

In the above example, the number of sound rays is not reduced up to thedepth L1 in at least one image (the transmission and reception for theimage A) at any temperature. However, this is not the sole case of theinvention and the number of sound rays may be performed beyond the depthL2 or L3 in the ultrasound transmission and reception for all the imagesdepending on the temperature.

An example of the ultrasound transmission and reception is conceptuallyshown in FIGS. 27A to 27C.

In this example, as in the above example, when the temperaturemeasurement result obtained with the temperature sensor 42 is less thanT7, the number of sound rays is not reduced in the transmission andreception for all the images A, B and C as shown in FIG. 27A. As in theabove example, when the temperature measurement result obtained with thetemperature sensor 42 is equal to or more than T7 but less than T8, thenumber of sound rays is not reduced in the transmission and receptionfor the image A but is reduced in the transmission and reception for theimages B and C beyond the depth L2 as shown in FIG. 27B.

In contrast, in this example, when the temperature measurement resultobtained with the temperature sensor 42 is equal to or more than T8, thenumber of sound rays is reduced in the transmission and reception forthe image A beyond the depth L2 and in the transmission and receptionfor the images B and C beyond the depth L3 as shown in FIG. 27C.

According to this example, the image quality of the resulting compositeultrasound image is reduced as s whole but the effect of preventing heatgeneration is increased.

In the above example, when the temperature measurement result obtainedwith the temperature sensor 42 is equal to or more than T7, the numberof sound rays is reduced in the region deeper than the predetermineddepth in the ultrasound transmission and reception for two images in oneframe but this is not the sole case of the invention. That is, based onthe temperature measurement result obtained with the temperature sensor42, the number of sound rays may be reduced beyond the predetermineddepth in the ultrasound transmission and reception for only one image inone frame or in the ultrasound transmission and reception for three ormore images in one frame.

Considering the purpose that the temperature increase within the probe12D is suppressed while minimizing the image quality deterioration dueto the temperature increase, when the temperature exceeds one of thethresholds, the number of sound rays is preferably reduced beyond thepredetermined depth in two or more images of one frame. In addition, inorder to suppress the temperature increase while preventing the imagequality deterioration, when the temperature exceeds one of thethresholds, the number of sound rays for all the images except the imageA (main image) is preferably reduced in the region beyond thepredetermined depth depending on the temperature.

In addition, in the above examples, since the predetermined number uponspatial compounding is three, two temperature thresholds are provided.However, this is not the sole case of the invention and in cases werethe predetermined number is four or more, three or more thresholds maybe provided.

The number of depths set for the reception signal processing dependingon the temperature is also not limited to three. For example, two depthsincluding the normal depth (L1) and the small depth (L3) may beprovided. Alternatively, four or more depths of reception signalprocessing may be provided by setting a plurality of medium depths suchas the depth L2-1 and the depth L2-2 between the normal depth L1 and thesmall depth L3.

In the examples shown in FIGS. 23A to 27C, the order of ultrasoundtransmission and reception in one frame is the same for all the frames.However, this is not the sole case of the invention and the order ofultrasound transmission and reception of the images in each frame may bedifferent.

For example, as shown in FIGS. 28A to 28C, the ultrasound transmissionand reception of the first frame, the second frame, the third frame, thefourth frame and the like may be performed in the orders of “imageB→image A→image C”, “image C→image A→image B”, “image B→image A→image C”and “image C→image A→image B” and the like, respectively.

That is, also in the fourth embodiment of the ultrasound diagnosticapparatus 10D, as in the first embodiment, the directions of ultrasoundtransmission and reception in the last ultrasound image in the earlierone of two consecutive frames (i.e., two temporally consecutivecomposite ultrasound images) and the first ultrasound image in thesubsequent frame may be the same.

This order of ultrasound transmission and reception enables theultrasound transmission and reception to be continued in the samedirections to facilitate the control of the transmission drive 30 andthe individual signal processors 20 a.

As described above, the reception signals outputted from the probe 12Dare supplied to the diagnostic apparatus body 14D by wirelesscommunication.

Similarly to the first embodiment of the diagnostic apparatus body 10Ashown in FIG. 1, the diagnostic apparatus body 14D includes an antenna50, a wireless communication unit 52, a serial/parallel converter 54, adata storage unit 56, an image generating unit 58, a display controller62, a monitor 64, a communication controller 68, an apparatus bodycontroller 70 and an operating unit 72.

As in the above embodiment, the diagnostic apparatus body 14D includes abuilt-in power supply unit (not shown), which supplies electric powerfor drive to each component.

The antenna 50, the wireless communication unit 52, the serial/parallelconverter 54, the data storage unit 56, the image generating unit 58,the display controller 62, the monitor 64, the communication controller68 and the apparatus body controller 70 are basically the same as thosein the diagnostic apparatus body 10A shown in FIG. 1.

More specifically, the wireless communication unit 52 performs wirelesscommunication with the probe 12D via the antenna 50 to transmit controlsignals to the probe 12D and receive signals sent from the probe 12D.The wireless communication unit 52 demodulates the received signals andoutputs them to the serial/parallel converter 54 as serial sample data.

The communication controller 68 controls the wireless communication unit52 so that various control signals are transmitted according to thesettings made by the apparatus body controller 70.

The serial/parallel converter 54 converts the serial sample data intoparallel sample data. The data storage unit 56 stores at least one frameof sample data converted by the serial/parallel converter 54.

The image generating unit 58 (phase adjusting and summing unit 76D,image processor 78 and image combining unit 80) performs receptionfocusing on sample data for each image read out from the data storageunit 56 to generate image signals representing an ultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10D, the probe 12D performs, forexample, the ultrasound transmission and reception for three images,that is, the transmission and reception for the images A, B and C.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 accordingly combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10D, the probe 12D reduces the number ofsound rays in the region beyond the predetermined depth as for thereception of the ultrasonic echoes based on the temperature measuredwith the temperature sensor 42. That is, the number of sound rays isreduced in the region of the ultrasound image beyond the predetermineddepth based on the temperature measured with the temperature sensor 42.

Upon spatial compounding, the phase adjusting and summing unit 76Dinterpolates the eliminated sound rays with the adjacent sound rays(surrounding sound rays) as to the ultrasound image in which the numberof sound rays is reduced in the region beyond the predetermined depth togenerate sound rays corresponding to those of the region where thenumber of sound rays was reduced, thus generating sound rays (sound raysignals) for the whole ultrasound image.

The interpolation method is not particularly limited but any knowninterpolation method implemented in various image processing steps canall be used.

The display controller 62 causes the monitor 64 to display theultrasound image according to the image signals generated by the imagegenerating unit 58.

Under the control of the display controller 62, the monitor 64 displaysthe ultrasound image.

The apparatus body controller 70 controls the components in thediagnostic apparatus body 14D. The apparatus body controller 70 isconnected to the operating unit 72 to perform various input operationsincluding as to whether or not spatial compounding is to be performed.

The operation of the ultrasound diagnostic apparatus 10D shown in FIG.20 is described below.

Similarly to the ultrasound diagnostic apparatus 10A, during thediagnosis, various kinds of information inputted to the operating unit72 are first sent to the probe 12D by wireless communication and thensupplied to the probe controller 38 also in the ultrasound diagnosticapparatus 10D.

Then, ultrasonic waves are transmitted from the transducers 18 inaccordance with the drive voltage supplied from the transmission drive30 of the probe 12D.

The reception signals outputted from the transducers 18 that havereceived the ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject are supplied to the corresponding individual signalprocessors 20 a to generate sample data.

In the probe 12D, when spatial compounding is performed, the temperaturemeasurement result of the signal processor 20 obtained with thetemperature sensor 42 is sent to the reception controller 34D.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10D, the probe 12D reduces the number ofsound rays in the regions of the ultrasound images beyond thepredetermined depth based on the temperature measurement results of thereception signal processor 20 obtained with the temperature sensor 42.More specifically, the probe 12D controls the drive of the individualsignal processors 20 a processing the reception signals such that thedepth beyond which the number of sound rays is reduced in any of theultrasound images to be combined is decreased in the order of “depthL1→depth L2→depth L3” each time the temperature exceeds one of thethresholds according to the temperature measurement results obtainedwith the temperature sensor 42.

For example, when the temperature measured with the temperature sensor42 is less than T7, the reception controller 34D controls the operationof the signal processor 20 (individual signal processors 20 a) so thatthe number of sound rays is not reduced in the transmission andreception for all the images A, B and C as shown in 23A.

When the temperature measured with the temperature sensor 42 is equal toor more than T7 but less than T8, the reception controller 34D controlsthe operation of the signal processor 20 so that the number of soundrays is not reduced in the transmission and reception for the image Abut is reduced in the transmission and reception for the images B and Cbeyond the depth L2 in one of every two frames as shown in FIG. 23B.

When the temperature measured with the temperature sensor 42 is equal toor more than T8, the reception controller 34D controls the operation ofthe signal processor 20 so that the number of sound rays is not reducedin the transmission and reception for the image A but is reduced in thetransmission and reception for the images B and C beyond the depth L3 inone of every two frames as shown in FIG. 23C.

The sample data generated by the individual signal processors 20 a aresent to the parallel/serial converter 24, where the sample data isconverted into serial data. The serial data is then wirelesslytransmitted from the wireless communication unit 26 (antenna 28) to thediagnostic apparatus body 14D.

The sample data received by the wireless communication unit 52 of thediagnostic apparatus body 14D converted into parallel data in theserial/parallel converter 54 and stored in the data storage unit 56.

Further, the sample data for each image is read out from the datastorage unit 56 to generate image signals of an ultrasound image in theimage generating unit 58. The display controller 62 causes the monitor64 to display the ultrasound image based on the image signals.

Upon spatial compounding, the phase adjusting and summing unit 76D ofthe image generating unit 58 interpolates the sound rays eliminated bythe probe 12D and then the image combining unit 80 combines theultrasound images.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10D, the probe 12D reduces the number ofsound rays in the ultrasound images to be combined beyond thepredetermined depth based on the temperature measurement results of thereception processor 20 obtained with the temperature sensor 42. Morespecifically, the probe 12D reduces the number of sound rays in any ofthe ultrasound images to be combined beyond the depth L2 or 13 based onthe temperature measurement result obtained with the temperature sensor42.

For example, in the example shown in FIGS. 23A to 23C, when thetemperature is less than T7 upon spatial compounding, the probe 12D doesnot reduce the number of sound rays in the ultrasound transmission andreception based on the temperature measurement result obtained with thetemperature sensor 42. When the temperature measured with thetemperature sensor 42 is equal to or more than T7 but less than T8, thenumber of sound rays is reduced in the region beyond the depth L2 in oneof every two frames. In addition, when the temperature measured with thetemperature sensor 42 is equal to or more than T8, the number of soundrays is reduced in the region beyond the depth L3 in one of every twoframes.

When spatial compounding is performed, the phase adjusting and summingunit 76D correspondingly interpolates the eliminated sound rays (theportions having no sound rays) with the surrounding sound rays as forthe image for which the number of sound rays is reduced in the regionbeyond the depth L2 or L3 to thereby generate sound rays correspondingto the whole area of one ultrasound image and sends the produced soundrays to the image combining unit 80.

When spatial compounding is performed, the image combining unit 80combines the ultrasound image A derived from the transmission andreception for the image A, the ultrasound image B derived from thetransmission and reception for the image B, and the ultrasound image Cderived from the transmission and reception for the image C which weregenerated in the phase adjusting and summing unit 76D to therebygenerate image signals for a composite ultrasound image, and outputs theimage signals to the display controller 62.

FIG. 29 is a conceptual block diagram showing an embodiment of theultrasound diagnostic apparatus according to the second aspect of theinvention.

Many components of the ultrasound diagnostic apparatus 10E shown in FIG.29 are the same as those of the ultrasound diagnostic apparatus 10Ashown in FIG. 1 except that the temperature sensor 42 is not provided.Therefore, like components are denoted by the same reference numeralsand the following description mainly focuses on the different features.

As in the first embodiment of the ultrasound diagnostic apparatus 10A,the ultrasound diagnostic apparatus 10E shown in FIG. 29 includes anultrasound probe 12E (hereinafter referred to as “probe 12E”) and adiagnostic apparatus body 14E. As in the above embodiment, theultrasound probe 12E is connected to the diagnostic apparatus body 14Eby wireless communication.

As in the first embodiment of the probe 12A, the probe 12E transmitsultrasonic waves to the subject, receives ultrasonic echoes generated byreflection of the ultrasound waves on the subject, and outputs receptionsignals of an ultrasound image in accordance with the receivedultrasonic echoes.

There is no limitation on the type of the probe 12E and various knownultrasound probes can be used.

As in the probe 12A, the probe 12E also includes a piezoelectric unit16, a signal processor 20, a parallel/serial converter 24, a wirelesscommunication unit 26, an antenna 28, a transmission drive 30, atransmission controller 32E, a reception controller 34E, a communicationcontroller 36 and a probe controller 38. As described above, the probe12E in this aspect includes no temperature sensor.

The probe 12E also includes a built-in battery (not shown), whichsupplies electric power for drive to each component.

The piezoelectric unit 16, the signal processor 20, the parallel/serialconverter 24, the wireless communication unit 26, the antenna 28, thetransmission drive 30, the communication controller 36 and the probecontroller 38 are basically the same as those of the probe 12A.

More specifically, the piezoelectric unit 16 is a one-dimensional ortwo-dimensional array of transducers 18 transmitting and receivingultrasonic waves.

The transmission drive 30 supplies the transducers 18 with a drivevoltage so that the transducers transmit ultrasonic waves so as to formultrasonic beams.

The transducers 18 output the reception signals of the ultrasonic echoesto individual signal processors 20 a of the signal processor 20. Asdescribed above, each individual signal processor 20 a has an AFE,processes the reception signals to generate sample data and supplies thegenerated sample data to the parallel/serial converter 24. Theparallel/serial converter 24 converts the parallel sample data intoserial sample data.

The ultrasound diagnostic apparatus 10E also has the function of spatialcompounding in which ultrasound images obtained by the ultrasoundtransmission and reception in mutually different directions are combinedto produce a composite ultrasound image.

Similarly to the above ultrasound diagnostic apparatus 10A, theultrasound diagnostic apparatus 10E combines, for example, threeultrasound images upon spatial compounding. Therefore, the transmissioncontroller 32E and the reception controller 34E control the drive of thetransmission drive 30 and the individual signal processors 20 a,respectively, such that three types of ultrasound transmission andreception are performed in mutually different directions of ultrasoundtransmission and reception.

When spatial compounding is performed, the transmission controller 32Eand the reception controller 34E of the probe 12E control the drive ofthe transmission drive 30 and the individual signal processors 20 a,respectively, such that the plurality of types of ultrasoundtransmission and reception are performed in a predetermined order.

When spatial compounding is performed in the ultrasound diagnosticapparatus 10E according to this aspect, the probe 12E makes thedirections of ultrasound transmission and reception in the lastultrasound image in the earlier one of two temporally consecutive frames(composite ultrasound images) coincide with those in the firstultrasound image in its subsequent frame. In other words, the lastultrasound image in the earlier one of two temporally consecutivecomposite ultrasound images is made to coincide with the firstultrasound image in its subsequent composite ultrasound image in thedirections of ultrasound transmission and reception.

This point will be described in detail later.

The wireless communication unit 26 generates transmission signals fromthe serial sample data and transmits the serial sample data to thediagnostic apparatus body 14E via the antenna 28.

The wireless communication unit 26 receives various control signals fromthe diagnostic apparatus body 14E and outputs the received controlsignals to the communication controller 36.

The communication controller 36 controls the wireless communication unit26. The communication controller 36 outputs the various control signalsreceived by the wireless communication unit 26 to the probe controller38.

The probe controller 38 controls various components of the probe 12Eaccording to various control signals transmitted from the diagnosticapparatus body 14E.

As described above, the ultrasound diagnostic apparatus 10E of theinvention has the function of producing an image (composite ultrasoundimage) through spatial compounding.

As in the ultrasound diagnostic apparatus 10A shown in FIG. 1, theultrasound diagnostic apparatus 10E also performs, for example, thethree types of ultrasound transmission and reception in mutuallydifferent directions upon spatial compounding as conceptually shown inFIG. 2. More specifically, upon spatial compounding, the probe 12Eperforms the three types of ultrasound transmission and reception,including the “transmission and reception for the image A” as theultrasound transmission and reception for obtaining the main image(image including the whole area of the composite ultrasound image formedby spatial compounding), the “transmission and reception for the imageB” in a direction inclined by an angle of θ with respect to thedirection of the transmission and reception for the image A, and the“transmission and reception for the image C” in a direction inclined byan angle of −θ with respect to the direction of the transmission andreception for the image A.

The diagnostic apparatus body 14E (more specifically an image combiningunit 80 to be described later) combines one to three ultrasound imagesselected from the ultrasound image A (solid line) as the main imageobtained by the transmission and reception for the image A, theultrasound image B (broken line) obtained by the transmission andreception for the image B, and the ultrasound image C (chain line)obtained by the transmission and reception for the image C according tothe number of types of ultrasound transmission and reception performedin each frame to thereby produce a composite ultrasound image coveringthe region of the ultrasound image A.

When spatial compounding is performed in the ultrasound diagnosticapparatus 10E, for example, a predetermined number of one to three)types of ultrasound transmission and reception which are selected fromthe three types including the transmission and reception for the imageA, those for the image B and those for the image C and which make up aframe unit for obtaining a composite ultrasound image are repeatedlyperformed on a frame basis.

As will be described later in detail, in the second aspect of theinvention, the number of types of ultrasound transmission and receptionin each frame upon spatial compounding may be the same in all the framesor a frame having a different number of types of ultrasound transmissionand reception may be included. That is, when spatial compounding isperformed in the ultrasound diagnostic apparatus 10E, the number ofultrasound images to be combined may be the same for all the compositeultrasound images or composite ultrasound images made from differentnumbers of ultrasound images may coexist.

In the practice of the invention, the number of types of ultrasoundtransmission and reception set to perform spatial compounding, that is,the maximum number of ultrasound images to be combined is not limited tothree. That is, the maximum number of ultrasound images to be combinedby spatial compounding may be two or four or more.

In addition, various known methods can be used to transmit and receiveultrasonic waves in different directions as in the above embodiments.

As described above, when spatial compounding is performed, the pluralityof types of ultrasound transmission and reception which are made inmutually different directions of ultrasound transmission and receptionand which make up a frame are repeatedly performed on a frame basis.

In normal spatial compounding, the plurality of types of ultrasoundtransmission and reception which are different in the directions ofultrasound transmission and reception are performed in each frame in thesame order. More specifically, when the transmission and reception forthe images A, B and C are performed as in the illustrated example, asconceptually shown in FIG. 30C, the ultrasound transmission andreception are repeatedly performed on a frame basis in the order of thetransmission and reception for the image A, those for the image B andthose for the image C which make up one frame. Therefore, in normalspatial compounding, the directions of ultrasound transmission andreception are to be changed each time the transmission and reception foreach image are performed.

In contrast, when spatial compounding is performed in the ultrasounddiagnostic apparatus 10E, the probe 12E makes the directions ofultrasound transmission and reception in the last ultrasound image inthe earlier one of two temporally consecutive frames (compositeultrasound images) coincide with those in the first ultrasound image inits subsequent frame. In other words, the last ultrasound image in theearlier one of two temporally consecutive composite ultrasound images ismade to coincide with the first ultrasound image in its subsequentcomposite ultrasound image in the directions of ultrasound transmissionand reception.

In other words, in the ultrasound diagnostic apparatus 10E of theinvention, the last ultrasound transmission and reception in the earlierone of two temporally consecutive frames is made to coincide with thefirst ultrasound transmission and reception in its subsequent frame inthe directions of ultrasound transmission and reception.

For example, as conceptually shown in FIG. 30A, the ultrasoundtransmission and reception of the first frame, the second frame, thethird frame, the fourth frame and the like are performed in the ordersof “image B→image A→image C”, “image C→image A→image B”, “image B→imageA→image C” (in the same order as the first frame), “image C→imageA→image B” the same order as the second frame) and the like,respectively. In other words, the ultrasound transmission and receptionin the order of “image B→image A→image C” and those in the order of“image C→image A→image B” are alternately repeated.

Alternatively, as conceptually shown in FIG. 30B, the ultrasoundtransmission and reception of the first frame, the second frame, thethird frame, the fourth frame and the like are performed in the ordersof “image A→image B→image C”, “image C→image B→image A”, “image A→imageB→image C” (in the same order as the first frame), “image C→imageB→image A” (in the same order as the second frame) and the like,respectively. In other words, the ultrasound transmission and receptionin the order of “image A→image B→image C” and those in the order of“image C→image B→image A” are alternately repeated.

In this aspect, when spatial compounding is thus performed, the lastimage in the earlier one of two temporally consecutive frames is made tocoincide with the first image in its subsequent frame in the directionsof ultrasound transmission and reception. In other words, the lastultrasound image in the earlier one of two temporally adjacent compositeultrasound images produced by spatial compounding and the firstultrasound image in the subsequent composite ultrasound image areobtained by the ultrasound transmission and reception in the samedirections.

Therefore, it is not necessary to change the directions of ultrasoundtransmission and reception between two adjacent frames, which cansimplify the control of the ultrasound transmission and reception in thetransmission drive 30 and the individual signal-processors 20 a, forexample when changing the control of the delay for changing thedirections of ultrasound transmission and reception. Accordingly, theillustrated ultrasound diagnostic apparatus 10E can reduce the burden ofthe probe 12E in spatial compounding.

Spatial compounding performed in the ultrasound diagnostic apparatus 10Eis not limited to the case where all the set types of ultrasoundtransmission and reception are performed in one frame. That is, in thisaspect, one frame of ultrasound images may be formed by any number oftypes of ultrasound transmission and reception if the number is equal toor smaller than the appropriately set predetermined number.

In other words, this aspect is not limited to the case where the setmaximum number of ultrasound images are combined by spatial compounding.

When spatial compounding is performed in the ultrasound diagnosticapparatus 10E, the number of types of ultrasound transmission andreception in one frame is not limited to three but may be two if thedirections of ultrasound transmission and reception in the lastultrasound image in one of two adjacent frames may coincide with thosein the first ultrasound image in its subsequent frame. That is, thenumber of ultrasound images to be combined in one frame by spatialcompounding may be two.

For example, high image quality mode in which three images are combinedand normal image quality mode in which two images are combined are setas spatial compounding modes so that one of three-image composition andtwo-image composition may be selected with an operating unit 72E to bedescribed later by any known method such as the GUI (graphical userinterface). Alternatively, the probe 12E may be provided with aselection means such as a switch. These modes are also applied to thecases shown in FIGS. 32A to 33B to be described later.

For example, as conceptually shown in FIG. 31A, the transmission andreception for the image A (main image) are not performed and theultrasound transmission and reception of the first frame, the secondframe, the third frame, the fourth frame and the like may be performedin the orders of “image B→image C”, “image C→image B”, “image B→image C”(in the same order as the first frame), “image C→image B” (in the sameorder as the second frame) and the like, respectively. In other words,the ultrasound transmission and reception in the order of “image B→imageC” and those in the order of “image C→image B” may be alternatelyrepeated.

When two ultrasound images are used to perform spatial compounding inthe ultrasound diagnostic apparatus 10E, frames may coexist in whichcombinations of types of ultrasound transmission and reception aredifferent.

That is, when the number of types of ultrasound transmission andreception used to perform special compounding is smaller than the setnumber, frames may coexist in which combinations of types of ultrasoundtransmission and reception are different. In other words, when thenumber of ultrasound images to be combined by spatial compounding issmaller than the set maximum number, composite ultrasound imagesobtained by combining ultrasound images which are different in thedirections of ultrasound transmission and reception may coexist.

For example, as conceptually shown in FIG. 31B, the ultrasoundtransmission and reception of the first frame, the second frame, thethird frame and the fourth frame may be performed in the orders of“image A→image B”, “image B→image A”, “image A→image C” and “imageC→image A”, respectively, and those of the first to fourth frames may berepeatedly performed.

In the practice of the invention, if the directions of the ultrasoundtransmission and reception in temporally adjacent frames coincide witheach other when spatial compounding is performed, frames which aredifferent in the number of types of ultrasound transmission andreception (the number of ultrasound images to be combined) may coexistin the predetermined number of temporally consecutive frames.

That is, in the practice of the invention, frames which are different inthe frame rate in spatial compounding may coexist.

For example, as conceptually shown in FIG. 32A, the ultrasoundtransmission and reception of the first and second frames may beperformed in the orders of “image B→image A→image C” and “image C→imageA→image B”, respectively, and those of the third and fourth frames beperformed so as to form two images such as “image B→image C” and “imageC→image B”, respectively, and those of the first to fourth frames berepeatedly performed.

Alternatively, as conceptually shown in FIG. 32B, the ultrasoundtransmission and reception of the first and second frames may beperformed in the orders of “image A→image B→image C” and “image C→imageB→image A”, respectively, and those of the third, fourth and fifthframes be performed so as to form two images such as “image A→image C”,“image C→image B” and “image B→image A”, respectively, those of thesixth and seventh frames be performed so as not to perform imagecomposition or to form only one image, that is, image A, and those ofthe first to seventh frames be repeatedly performed.

The predetermined number of temporally consecutive frames is not limitedto four and seven as in the above cases but may be five, six or eight ormore. The transmission and reception for the image A serving as the mainimage are preferably performed for the frames in which one type ofultrasound transmission and reception is only performed.

In addition, in the ultrasound diagnostic apparatus 10E according tothis aspect, the ultrasound transmission and reception may be sharedbetween the last ultrasound image in the earlier one of two temporallyadjacent frames and the first ultrasound image in the subsequent frameso that the directions of ultrasound transmission and reception in thelast ultrasound image may coincide with those in the first ultrasoundimage.

In other words, in two temporally adjacent composite ultrasound images,one ultrasound image may serve as both of the last ultrasound image inthe earlier composite ultrasound image and the first ultrasound imagethe subsequent composite ultrasound image.

For example when spatial compounding is performed according to theexample shown in FIG. 32A, as conceptually shown in FIG. 33A, thepattern of ultrasound transmission and reception of “image B→imageA→image C→image A→image B→image C→image B” is repeatedly performed.

The first three images of “image B→image A→image C” are used as thefirst frame. The image C is shared between the last image in the firstframe and the first image in the second frame and the three imagesstarting from the third image C: “image C→image A→image B” are used asthe second frame. The image B is shared between the last image in thesecond frame and the first image in the third frame and the two imagesstarting from the fifth image B: “image B→image C” are used as the thirdframe. In addition, The image C is shared between the last image in thethird frame and the first image in the fourth frame and the two imagesstarting from the sixth image C: “image C→image B” are used as thefourth frame, and the ultrasound transmission and reception of the firstto fourth frames are repeatedly performed.

In this case, the image B may be shared between the last image in thefourth frame and the first image in the first frame.

When spatial compounding is performed according to the example shown inFIG. 32B, as conceptually shown in FIG. 33B, the pattern of ultrasoundtransmission and reception of “image A→image B→image C→image B→imageA→image C→image B→image A→image A→image A” is repeatedly performed.

The first three images of “image A→image B→image C” are used as thefirst frame. The image C is shared between the last image in the firstframe and the first image in the second frame and the three imagesstarting from the third image C: “image C→image B→image A” are used asthe second frame. The image A is shared between the last image in thesecond frame and the first image in the third frame and the two agesstarting from the fifth image A: “image A→image C” are used as the thirdframe. The image C is shared between the last image in the third frameand the first image in the fourth frame and the two images starting fromthe sixth image C: “image C→image B” are used as the fourth frame. Theimage B is shared between the last image in the fourth frame and thefirst image in the fifth frame and the two images starting from theseventh image B: “image B→image A” are used as the fifth frame. Inaddition, the image A as the ninth image and the image A as the tenthimage are used as the sixth frame and seventh frame, respectively, andthe ultrasound transmission and reception of the first to seventh framesare repeatedly performed.

In this case, the image A may be shared between the image in the seventhframe and the first image in the first frame.

By thus sharing the ultrasound transmission and reception (ultrasoundimages to be used for composition) between adjacent frames, thecomposite ultrasound images can be produced by spatial compounding athigher speeds.

As described above, the reception signals outputted from the probe 12Eare supplied to the diagnostic apparatus body 14E by wirelesscommunication.

Similarly to the first embodiment of the diagnostic apparatus body 10Ashown in FIG. 1, the diagnostic apparatus body 14E includes an antenna50, a wireless communication unit 52, a serial/parallel converter 54, adata storage unit 56, an image generating unit 58, a display controller62, a monitor 64, a communication controller 68, an apparatus bodycontroller 70 and the operating unit 72E.

As in the above embodiment, the diagnostic apparatus body 14E includes abuilt-in power supply unit (not shown), which supplies electric powerfor drive to each component.

The antenna 50, the wireless communication unit 52, the serial/parallelconverter 54, the data storage unit 56, the image generating unit 58,the display controller 62, the monitor 64, the communication controller68 and the apparatus body controller 70 are basically the same as thosein the diagnostic apparatus body 10A shown in FIG. 1.

More specifically, the wireless communication unit 52 performs wirelesscommunication with the probe 12E via the antenna 50 to transmit controlsignals to the probe 12E and receive signals sent from the probe 12E.The wireless communication unit 52 demodulates the received signals andoutputs them to the serial/parallel converter 54 as serial sample data.

The communication controller 68 controls the wireless communication unit52 so that various control signals are transmitted according to thesettings made by the apparatus body controller 70.

The serial/parallel converter 54 converts the serial sample data intoparallel sample data. The data storage unit 56 stores at least one frameof sample data converted by the serial/parallel converter 54.

The image generating unit 58 (phase adjusting and summing unit 76, imageprocessor 78 and image combining unit 80) performs reception focusing onsample data for each image read out from the data storage unit 56 togenerate image signals representing an ultrasound image.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10E, the probe 12E performs, forexample, the ultrasound transmission and reception for three images,that is, the transmission and reception for the images A, B and C.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 accordingly combines the ultrasound image Aderived from the transmission and reception for the image A, theultrasound image B derived from the transmission and reception for theimage B, and the ultrasound image C derived from the transmission andreception for the image C to generate image signals for a compositeultrasound image.

Alternatively, when two types of ultrasound transmission and receptionare used in spatial compounding as shown in FIGS. 31A and 31B, the imagecombining unit 80 combines two ultrasound images.

The image combining unit 80 performs no image composition in a framewhere only one type of ultrasound transmission and reception isperformed as seen in the example shown in FIG. 32B and an ultrasoundimage sent from the image processor 78 is used as the image signals of acomposite ultrasound image.

The display controller 62 causes the monitor 64 to display theultrasound image according to the image signals generated by the imagegenerating unit 58.

Under the control of the display controller 62, the monitor 64 displaysthe ultrasound image.

The apparatus body controller 70 controls the components in thediagnostic apparatus body 14E. The apparatus body controller 70 isconnected to the operating unit 72E to perform various input operationsfor the selection of the number of images to be combined or as towhether or not spatial compounding is to be performed.

The operation of the ultrasound diagnostic apparatus 10E shown in FIG.29 is described below.

Similarly to the ultrasound diagnostic apparatus 10A, during thediagnosis, various kinds of information inputted to the operating unit72E are first sent to the probe 12E by wireless communication and thensupplied to the probe controller 38 also in the ultrasound diagnosticapparatus 10E.

Then, ultrasonic waves are transmitted from the transducers 18 inaccordance with the drive voltage supplied from the transmission drive30 of the probe 12E.

The reception signals outputted from the transducers 18 that havereceived the ultrasonic echoes generated by reflection of the ultrasonicwaves on the subject are supplied to the corresponding individual signalprocessors 20 a to generate sample data.

As described above, when spatial compounding is performed in theultrasound diagnostic apparatus 10E, the probe 12E performs ultrasoundtransmission and reception so that the last ultrasound image in theearlier one of two temporally consecutive frames (i.e., compositeultrasound images) is made to coincide with the first ultrasound imagein its subsequent frame in the directions of ultrasound transmission andreception.

For example, the transmission controller 32E and the receptioncontroller 34E control the operations of the transmission drive 30 andthe signal processor 20 (individual signal processors 20 a) so that thetransmission and reception for the “image B→image A→image C” and thosefor the “image C→image A→image B” are alternately repeated as shown inFIG. 30A.

Alternatively, two types of ultrasound transmission and reception may beused in one frame as shown in FIGS. 31A and 31B, or frames which aredifferent in the number of types of ultrasound transmission andreception may coexist as shown in FIGS. 32A and 32B. In addition, theultrasound transmission and reception may be shared between the lastimage in the earlier one of temporally adjacent frames and the firstimage in the subsequent frame as shown in FIGS. 33A and 33B.

The sample data generated by the individual signal processors 20 a aresent to the parallel/serial converter 24, where the sample data isconverted into serial data. The serial data is then wirelesslytransmitted from the wireless communication unit 26 (antenna 28) to thediagnostic apparatus body 14E.

The sample data received by the wireless communication unit 52 of thediagnostic apparatus body 14E is converted into parallel data in theserial/parallel converter 54 and stored in the data storage unit 56.

Further, the sample data for each image is read out from the datastorage unit 56 to generate image signals of an ultrasound image in theimage generating unit 58. The display controller 62 causes the monitor64 to display the ultrasound image based on the image signals.

When spatial compounding is performed, the image combining unit 80 ofthe image generating unit 58 combines the ultrasound images.

More specifically, when spatial compounding is performed in theultrasound transmission and reception as shown in FIGS. 30A to 30C, theimage combining unit 80 combines the ultrasound image A derived from thetransmission and reception for the image A, the ultrasound image Bderived from the transmission and reception for the image B, and theultrasound image C derived from the transmission and reception for theimage C to generate image signals for a composite ultrasound image, andoutputs the image signals to the display controller 62.

Alternatively, when two types of ultrasound transmission and receptionare used in spatial compounding as shown in FIGS. 31A and 31B, twoultrasound images are combined to generate image signals of a compositeultrasound image. In a frame where only one type of ultrasoundtransmission and reception is performed as shown in FIG. 32B, anultrasound image sent from the image processor 78 is not combined withother but is directly used as the image signals of a compositeultrasound image.

In the above-described embodiments, the illustrated ultrasounddiagnostic apparatus 10A to 10E are each configured so that the probehas a means for controlling ultrasound transmission and reception and ameans for processing reception signals obtained from ultrasonic echoesfrom a subject and the probe is connected to the diagnostic apparatusbody by wireless communication. However, this is not the sole case ofthe invention.

This invention is also applicable to an ultrasound diagnostic apparatusconfigured so that a wired connection established between the ultrasoundprobe and the diagnostic apparatus body, the ultrasound probe onlyincludes a piezoelectric unit and the diagnostic apparatus body controlsthe ultrasound transmission and reception.

However, as described above, this invention enables the control of theultrasound transmission and reception to be simplified while suppressingthe heat generation from the probe when spatial compounding isperformed.

Therefore, when spatial compounding is performed, heat generation fromor burden of the probe which is required to perform larger amounts ofoperation control and signal processing can be reduced by making use ofthe invention in an apparatus having a signal processing function and amechanism for controlling ultrasound transmission and receptionincorporated in the small probe, as exemplified by the illustratedultrasound diagnostic apparatus in which the probe is wirelesslyconnected to the diagnostic apparatus body. Therefore, this inventioncan be advantageously used in an ultrasound diagnostic apparatusconfigured so that a probe includes a mechanism for controllingultrasound transmission and reception.

The illustrated ultrasound diagnostic apparatus 10A to 10E individuallyinclude the spatial compounding functions in the first to fourthembodiments in the first aspect of the invention and the spatialcompounding function in the second aspect of the invention. However,this is not the sole case of the invention.

In other words, the ultrasound diagnostic apparatus of the invention hastwo or more functions selected from the functions according to the firstto fourth embodiments in the first aspect of the invention and thefunction in the second aspect of the invention so that a suitable modecan be selected to determine as to which spatial compounding function isto be performed.

While the ultrasound diagnostic apparatus of the invention has beendescribed above in detail, the invention is by no means limited to theabove embodiments, and various improvements and modifications may bemade without departing from the scope and spirit of the invention.

What is claimed is:
 1. An ultrasound diagnostic apparatus comprising: anultrasound probe configured to transmit ultrasonic waves into a subjectand receive ultrasonic echoes generated by reflection of the ultrasonicwaves from the subject, the ultrasound probe including a signalprocessor for processing reception signals based on the ultrasonicechoes and a temperature sensor for measuring a temperature at apredetermined position; and a diagnostic apparatus body configured togenerate ultrasound images in accordance with the reception signalsprocessed in the signal processor of said ultrasound probe, wherein saidultrasound probe is configured to perform a plurality of types ofultrasound transmission and reception in mutually different directionsof ultrasound transmission and reception and said diagnostic apparatusbody is configured to combine ultrasound images based on each of theplurality of types of ultrasound transmission and reception, andwherein, upon production of the composite ultrasound image in saiddiagnostic apparatus body, said ultrasound probe performs the ultrasoundtransmission and reception for producing said composite ultrasound imagethrough said plurality of types of ultrasound transmission and receptionor through at least one type of ultrasound transmission and receptionafter reduction of one or more types of ultrasound transmission andreception from said plurality of types of ultrasound transmission andreception based on a temperature measurement result obtained with saidtemperature sensor.
 2. The ultrasound diagnostic apparatus according toclaim 1, wherein said temperature sensor measures a temperature of saidsignal processor.
 3. The ultrasound diagnostic apparatus according toclaim 1, wherein, upon the production of the composite ultrasound imagein said diagnostic apparatus body, said ultrasound probe performsultrasound transmission and reception for obtaining a main image as anultrasound image in a preset predetermined output region by one of saidplurality of types of ultrasound transmission and reception.
 4. Theultrasound diagnostic apparatus according to claim 1, wherein the signalprocessor changes and sets a number of types of ultrasound transmissionand reception in said mutually different directions of ultrasoundtransmission and reception depending on the temperature measurementresult obtained with said temperature sensor, and the signal processorsets a temperature T1 and a temperature T2 higher than the temperatureT1 as thresholds and, upon the production of the composite ultrasoundimage in said diagnostic apparatus body, depending on the temperaturemeasurement result obtained with said temperature sensor, saidultrasound probe performs said plurality of types of ultrasoundtransmission and reception when the temperature measurement result isless than the temperature T1, performs a set minimum number of types ofultrasound transmission and reception when the temperature measurementresult is equal to or more than the temperature T2, and performs a givennumber of types of ultrasound transmission and reception which issmaller than the number of said plurality of types of transmission andreception but is larger than the set minimum number of types ofultrasound transmission and reception when the temperature measurementresult is equal to or more than the temperature T1 but less than thetemperature T2.
 5. The ultrasound diagnostic apparatus according toclaim 1, wherein the signal processor changes and sets a number of typesof ultrasound transmission and reception in said mutually differentdirections of ultrasound transmission and reception depending on thetemperature measurement result obtained with said temperature sensor,and the signal processor sets a temperature T1 and a temperature T2higher than the temperature T1 as thresholds and, upon the production ofthe composite ultrasound image in said diagnostic apparatus body,depending on the temperature measurement result obtained with saidtemperature sensor, said ultrasound probe performs said plurality oftypes of ultrasound transmission and reception when the temperaturemeasurement result is less than the temperature T1, and when thetemperature measurement result is equal to or more than said temperatureT1, performs, in one ultrasound image, the at least one type ofultrasound transmission and reception after the reduction of the one ormore types of ultrasound transmission and reception from said pluralityof types of ultrasound transmission and reception and performs, in itstemporally consecutive ultrasound image, said plurality of types ofultrasound transmission and reception or the at least one type ofultrasound transmission and reception after the reduction of the one ormore types of ultrasound transmission and reception from said pluralityof types of ultrasound transmission and reception, a specified number oftypes of ultrasound transmission and reception reduced from the numberof said plurality of types of ultrasound transmission and receptionbeing different in two consecutive ultrasound images including the oneultrasound image and its temporally consecutive ultrasound image.
 6. Theultrasound diagnostic apparatus according to claim 5, wherein saidultrasound probe performs the specified number of types of theultrasound transmission and reception by reducing the one or more typesof ultrasound transmission and reception from said plurality of types ofultrasound transmission and reception in one of the two temporallyconsecutive ultrasound images when the temperature sensor has thetemperature measurement result that is equal to or more than thetemperature T1 but less than the temperature T2.
 7. The ultrasounddiagnostic apparatus according to claim 6, wherein said ultrasound probeperforms the specified number of types of the ultrasound transmissionand reception by reducing the one or more types of ultrasoundtransmission and reception from said plurality of types of ultrasoundtransmission and reception in both of the two temporally consecutiveultrasound images when the temperature sensor has the temperaturemeasurement result that is equal to or more than the temperature T2. 8.The ultrasound diagnostic apparatus according to claim 1, wherein saidultrasound probe transmits and receives the ultrasonic waves inidentical directions for a last ultrasound image in one compositeultrasound image and a first ultrasound image in its temporallyconsecutive ultrasound image.
 9. The ultrasound diagnostic apparatusaccording to claim 1, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, said ultrasoundprobe performs the ultrasound transmission and reception so as to reducetemporally consecutive ultrasound image when two or more types ofultrasound transmission and reception are reduced from said plurality oftypes of ultrasound transmission and reception.
 10. The ultrasounddiagnostic apparatus according to claim 1, wherein, upon the productionof the composite ultrasound image in said diagnostic apparatus body,said ultrasound probe performs the ultrasound transmission and receptionso as to reduce a last ultrasound image in a composite ultrasound imageand a first ultrasound image in its temporally consecutive compositeultrasound image when the one or more types of ultrasound transmissionand reception are reduced from said plurality of types of ultrasoundtransmission and reception.
 11. The ultrasound diagnostic apparatusaccording to claim 1, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, said ultrasoundprobe adjusts conditions of the ultrasound transmission and reception soas to change an image quality of an ultrasound image to be combined insaid diagnostic apparatus body in accordance with the temperaturemeasurement result obtained with said temperature sensor.
 12. Theultrasound diagnostic apparatus according to claim 11, wherein saidtemperature sensor measures a temperature of said signal processor. 13.The ultrasound diagnostic apparatus according to claim 11, wherein saidultrasound probe changes at least one of a number of available channelsand a number of sound rays to adjust the conditions of the ultrasoundtransmission and reception.
 14. The ultrasound diagnostic apparatusaccording to claim 11, wherein a temperature T3 and a temperature T4higher than the temperature T3 are set as thresholds, and whereinultrasound transmission and reception at a normal image quality levelcorresponding to ultrasound images of predetermined image quality,ultrasound transmission and reception at a low image quality levelcorresponding to ultrasound images of lowest image quality, andultrasound transmission and reception at a medium image quality levelcorresponding to ultrasound images having image quality lower than thenormal image quality level but higher than the low image quality levelare set in the conditions of the ultrasound transmission and receptionfor obtaining the ultrasound image to be combined.
 15. The ultrasounddiagnostic apparatus according to claim 14, wherein, upon the productionof the composite ultrasound image in said diagnostic apparatus body,depending on the temperature measurement result obtained with saidtemperature sensor, said ultrasound probe performs all of said pluralityof types of ultrasound transmission and reception at the normal imagequality level when the temperature measurement result is less than thetemperature T3.
 16. The ultrasound diagnostic apparatus according toclaim 15, wherein, upon the production of the composite ultrasound imagein said diagnostic apparatus body, depending on the temperaturemeasurement result obtained with said temperature sensor, saidultrasound probe performs at least two of said plurality of types ofultrasound transmission and reception at the medium image quality levelwhen the temperature measurement result is equal to or more than thetemperature T3 but less than the temperature T4 and at the low imagequality level when the temperature measurement result is equal to ormore than the temperature T4.
 17. The ultrasound diagnostic apparatusaccording to claim 15, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, depending on thetemperature measurement result obtained with said temperature sensor,said ultrasound probe performs at least two of said plurality of typesof ultrasound transmission and reception at the medium image qualitylevel when the temperature measurement result is equal to or more thanthe temperature T3 but less than the temperature T4, and performs atleast one of said plurality of types of ultrasound transmission andreception at the medium image quality level and one or more types ofultrasound transmission and reception except said at least one of saidplurality of types of ultrasound transmission and reception at the lowimage quality level when the temperature measurement result is equal toor more than the temperature T4.
 18. The ultrasound diagnostic apparatusaccording to claim 14, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, depending on thetemperature measurement result obtained with said temperature sensor,said ultrasound probe performs at least two of said plurality of typesof ultrasound transmission and reception at the medium image qualitylevel when the temperature measurement result is equal to or more thanthe temperature T3 but less than the temperature T4, and performs the atleast two of said plurality of types of ultrasound transmission andreception at the low image quality level and all of one or more types ofultrasound transmission and reception except said at least two of saidplurality of types of ultrasound transmission and reception at themedium image quality level when the temperature measurement result isequal to or more than the temperature T4.
 19. The ultrasound diagnosticapparatus according to claim 14, wherein, upon the production of thecomposite ultrasound image in said diagnostic apparatus body, saidultrasound probe performs ultrasound transmission and reception forobtaining a main image as an ultrasound image in a preset predeterminedoutput region by one of said plurality of types of ultrasoundtransmission and reception and wherein the ultrasound transmission andreception for the main image are performed at the normal image qualitylevel.
 20. The ultrasound diagnostic apparatus according to claim 11,wherein said ultrasound probe transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.
 21. The ultrasounddiagnostic apparatus according to claim 1, wherein, upon the productionof the composite ultrasound image in said diagnostic apparatus body,said ultrasound probe adjusts a depth of the reception signals to beprocessed by said signal processor so as to change a depth of anultrasound image to be combined in said diagnostic apparatus body inaccordance with the temperature measurement result obtained with saidtemperature sensor.
 22. The ultrasound diagnostic apparatus according toclaim 21, wherein said temperature sensor measures a temperature of saidsignal processor.
 23. The ultrasound diagnostic apparatus according toclaim 21, wherein a temperature T5 and a temperature T6 higher than thetemperature T5 are set as thresholds and wherein a normal depthaccording to which the reception signals are processed up to apredetermined depth, a small depth according to which the receptionsignals are processed up to a shallowest depth and a medium depthaccording to which the reception signals are processed up to a depthsmaller than said normal depth but larger than said small depth are setfor the depth of the reception signals to be processed by said signalprocessor.
 24. The ultrasound diagnostic apparatus according to claim23, wherein, upon the production of the composite ultrasound image insaid diagnostic apparatus body, depending on the temperature measurementresult obtained with said temperature sensor, said ultrasound probeperforms all of reception signal processing in said plurality of typesof ultrasound transmission and reception up to the normal depth when thetemperature measurement result is less than the temperature T5.
 25. Theultrasound diagnostic apparatus according to claim 24, wherein, upon theproduction of the composite ultrasound image in said diagnosticapparatus body, depending on the temperature measurement result obtainedwith said temperature sensor, said ultrasound probe performs receptionsignal processing in at least two of said plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6 and up to the small depth when thetemperature measurement result is equal to or more than the temperatureT6.
 26. The ultrasound diagnostic apparatus according to claim 24,wherein, upon the production of the composite ultrasound image in saiddiagnostic apparatus body, depending on the temperature measurementresult obtained with said temperature sensor, said ultrasound probeperforms reception signal processing at least two of said plurality oftypes of ultrasound transmission and reception up to the medium depthwhen the temperature measurement result is equal to or more than thetemperature T5 but less than the temperature T6, and alternately repeatsreception signal processing up to the small depth in at least two ofsaid plurality of types of ultrasound transmission and reception andreception signal processing up to the medium depth in the at least twoof said plurality of types of ultrasound transmission and reception intemporally consecutive composite ultrasound images when the temperaturemeasurement result is equal to or more than the temperature T6.
 27. Theultrasound diagnostic apparatus according to claim 24, wherein, upon theproduction of the composite ultrasound image in said diagnosticapparatus body, depending on the temperature measurement result obtainedwith said temperature sensor, said ultrasound probe performs receptionsignal processing in at least two of said plurality of types ofultrasound transmission and reception up to the medium depth when thetemperature measurement result is equal to or more than the temperatureT5 but less than the temperature T6 and performs reception signalprocessing in at least one of said plurality of types of ultrasoundtransmission and reception up to the medium depth and one or more typesof ultrasound transmission and reception except said at least one ofsaid plurality of types of ultrasound transmission and reception up tothe small depth when the temperature measurement result is equal to ormore than the temperature T6.
 28. The ultrasound diagnostic apparatusaccording to claim 27, wherein ultrasound images subjected to thereception signal processing up to said medium depth and ultrasoundimages subjected to the reception signal processing up to said smalldepth are different in order of processing in temporally consecutivecomposite ultrasound images when the temperature measurement result isequal to or more than the temperature T6.
 29. The ultrasound diagnosticapparatus according to claim 24, wherein, upon the production of thecomposite ultrasound image in said diagnostic apparatus body, dependingon the temperature measurement result obtained with said temperaturesensor, said ultrasound probe performs reception signal processing in atleast two of said plurality of types of ultrasound transmission andreception up to the medium depth when the temperature measurement resultis equal to or more than the temperature T5 but less than thetemperature T6 and performs the reception signal processing in the atleast two of said plurality of types of ultrasound transmission andreception up to the small depth and all of one or more types ofultrasound transmission and reception except said at least two of saidplurality of types of ultrasound transmission and reception up to themedium depth when the temperature measurement result is equal to or morethan the temperature T6.
 30. The ultrasound diagnostic apparatusaccording to claim 23, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, said ultrasoundprobe performs ultrasound transmission and reception for obtaining amain image as an ultrasound image in a preset predetermined outputregion by one of said plurality of types of ultrasound transmission andreception and wherein reception signals obtained by the ultrasoundtransmission and reception for the main image are processed up to thenormal depth.
 31. The ultrasound diagnostic apparatus according to claim21, wherein said ultrasound probe transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.
 32. The ultrasounddiagnostic apparatus according to claim 1, wherein, upon the productionof the composite ultrasound image in said diagnostic apparatus body,said ultrasound probe adjusts reception signal processing performed bysaid signal processor so as to reduce a number of sound rays in a regionbeyond a predetermined depth in an ultrasound image to be combined bysaid diagnostic apparatus body depending on the temperature measurementresult obtained with said temperature sensor, and wherein, upon theproduction of the composite ultrasound image in said diagnosticapparatus body, said diagnostic apparatus body interpolates sound rayseliminated beyond said predetermined depth with their surrounding soundrays to produce said ultrasound image.
 33. The ultrasound diagnosticapparatus according to claim 32, wherein said temperature sensormeasures a temperature of said signal processor.
 34. The ultrasounddiagnostic apparatus according to claim 32, wherein a temperature T7 anda temperature T8 higher than the temperature T7 are set as thresholds,and wherein a normal depth up to which the number of sound rays is notreduced, a small depth which is shallowest, and a medium depth which issmaller than said normal depth but is larger than said small depth areset for the predetermined depth beyond which the number of sound rays isreduced.
 35. The ultrasound diagnostic apparatus according to claim 34,wherein, upon the production of the composite ultrasound image in saiddiagnostic apparatus body, depending on the temperature measurementresult obtained with said temperature sensor, said ultrasound probeprocesses all of ultrasound images up to the normal depth when thetemperature measurement result is less than the temperature T7.
 36. Theultrasound diagnostic apparatus according to claim 35, wherein, upon theproduction of the composite ultrasound image in said diagnosticapparatus body, depending on the temperature measurement result obtainedwith said temperature sensor, said ultrasound probe reduces the numberof sound rays beyond said medium depth in at least two of ultrasoundimages when the temperature measurement result is equal to or more thanthe temperature T7 but less than the temperature T8, and reduces thenumber of sound rays beyond said small depth in the at least two ofultrasound images when the temperature measurement result is equal to ormore than the temperature T8.
 37. The ultrasound diagnostic apparatusaccording to claim 35, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, depending on thetemperature measurement result obtained with said temperature sensor,said ultrasound probe reduces the number of sound rays beyond saidmedium depth in at least two of ultrasound images when the temperaturemeasurement result is equal to or more than the temperature T7 but lessthan the temperature T8, and reduces the number of sound rays beyondsaid medium depth in at least one of ultrasound images and one or moreultrasound images except said at least one of ultrasound images beyondsaid small depth when the temperature measurement result is equal to ormore than the temperature T8.
 38. The ultrasound diagnostic apparatusaccording to claim 35, wherein, upon the production of the compositeultrasound image in said diagnostic apparatus body, depending on thetemperature measurement result obtained with said temperature sensor,said ultrasound probe reduces the number of sound rays beyond saidmedium depth in at least two of ultrasound images when the temperaturemeasurement result is equal to or more than the temperature T7 but lessthan the temperature T8, and reduces the number of sound rays beyondsaid small depth in the at least two of ultrasound images and all of oneor more ultrasound images except said at least two of ultrasound imagesbeyond said medium depth when the temperature measurement result isequal to or more than the temperature T8.
 39. The ultrasound diagnosticapparatus according to claim 34, wherein, upon the production of thecomposite ultrasound image in said diagnostic apparatus body, saidultrasound probe performs ultrasound transmission and reception forobtaining a main image as an ultrasound image in a preset predeterminedoutput region by one of said plurality of types of ultrasoundtransmission and reception and wherein an ultrasound image obtained bythe ultrasound transmission and reception for the main image has thenormal depth.
 40. The ultrasound diagnostic apparatus according to claim32, wherein said ultrasound probe transmits and receives the ultrasonicwaves in identical directions for a last ultrasound image in onecomposite ultrasound image and a first ultrasound image in itstemporally consecutive composite ultrasound image.
 41. The ultrasounddiagnostic apparatus according to claim 1, wherein, wherein saidtemperature sensor measures a temperature of said signal processor, andan internal temperature of the ultrasound probe is controlled based onheat generation in the signal processor as indicated by the measuredtemperature of said signal processor, the signal processor changing anumber of types of ultrasound transmission and reception in saidmutually different directions of ultrasound transmission and receptiondepending on the measured temperature of said signal processor,including i) reducing the number of types of ultrasound transmission andreception in said mutually different directions of ultrasoundtransmission and reception to a first reduced number of types when themeasured temperature of said signal processor increases over a firstthreshold temperature, and ii) reducing the number of types ofultrasound transmission and reception in said mutually differentdirections of ultrasound transmission and reception to a second reducednumber of types when the measured temperature of said signal processorincreases over a second threshold temperature, the second reduced numberof types being less than the first reduced number of types and thesecond threshold temperature being greater than the first thresholdtemperature.